Why is Dropbox shutting down Mailbox? Why did it fail?

If the guy who sold you briefcases and folios, also wanted to become your courier service and then decided to also make photo frames and postcards, would you end up spending more of your money with that guy ? That was the case with Dropbox's portfolio utility for Mailbox and Carousel. 

Why did Mailbox fail and why is Dropbox likely to face stronger headwinds ? 

Files and documents are mechanisms designed to work with the world of paper record keeping. Much of the value in modern day professional and personal life comes from flow and analysis of information, quite often in real time. Much as in music where people are moving from buying and storing files to streaming on-demand, in enterprise and personal space people are moving to ubiquitous data. Ubiquitous data gets embedded within applications and flows dynamically across applications. With the cost/gigabyte of storage approaching zero, file sharing is fast becoming a feature that operates invisibly with no customer making 'Learn-Try-Buy' choices based on that criteria. I was an early user of both Dropbox and Mailbox . As seen from growth of tools like Slack, the rise of ubiquitous computing and ubiquitous data will increase valuation and market opportunity for applications that operating in the data flow and analysis space. These applications will focus less on the document formats , the formats that dropbox, box, mailbox, carousel and such other apps deeply rely on. 

Great entry in the arena..now to chase the ball!

Dropbox, Box and such other  tools entered the information market at its most easy port of easy entry -  record-keeping and file sharing. But they had to evolve into an information sharing and workflow platform. There is a fundamental flaw in thinking that a consumer's desire to store files on your platform will automatically lead to them gravitating towards using products based on storage.Storage decisions rarely drive economic decisions on anything that is not a perishable.  

The personal data storage market is massive and will spawn tens or maybe even hundreds of customer segments based on the configuration of different types of data, uses and flow in the lives of each customer segment. For example, an avid prosumer of design and aesthetic data (photos, brochures, catalogs) has a unique set of data and file storage needs in terms of flow ( shot on smartphone, edited on tablet, posted on Instagram and 500px, archived for use in the annual christmas card etc). But none of the customer segments will evolve from being on a particular file-sharing platform. In the enterprise software space, Geoffrey Moore's model of systems of record and systems of engagement is a centerpiece of many product strategy conversations. Those archetypes are also valid in the consumer space. A typical user is not looking to pay for a system of record if they can buy a system of engagement that comes bundled with the system of record. If I can buy a platform of software that helps me do all of my tasks and not deal with managing file formats and storage structures, I will prefer that platform. The earliest version of such a platform was the Windows and Mac Operating systems for the desktop world. Windows and Mac made the cost of hard-disk drive storage and associated decisions seem less important in the scheme of decisions for a typical computer user and forced a bit of standardization and thus ushered high volume PC usage.  Anyone who bet on file storage and sharing software in the 1990s had to learn to get embedded into a larger enterprise or PC software platform. Dropbox and Box have to prepare for that same scenario. 

Now why did Dropbox shutdown Mailbox and Carousel ?

Mailbox and Carousel failed to gain a substantive marketshare in an already crowded market right when Dropbox's core market for file storage and sharing is getting deeply discounted and unit margins for storage are negative. Economics of software development and sustenance tend to be high on operating costs even though capital costs maybe substantially lower than those in other businesses. If a part of your business is not growing at a pace faster than growth of the overall market, it makes no sense to burn operating cash on it; unless you know that the lagging business is a core competence required for scaling the rest of your business. 

I like Dropbox and Box and started off as an early user on both platforms , so I'll place an equanimous bet on these two hypothetical scenarios - 

1. Box, Dropbox and other such players will get subsumed by one of the larger players in the enterprise space or late entrants in the B2C space that need to gain a foothold - Microsoft/Dell/Oracle/SAP/HP/Xerox/Samsung.  Amazon, Google and Apple don't need these firms because they have their own storage platforms with substantive user base. I am almost willing to bet that Box will be acquired by Microsoft at some time in the next 5 years, especially if Box is able to get traction in healthcare and a couple of other segments. 
2. They will successfully pivot into being players focussed on specific user segments through one of these two strategies -
1. Building a string of workflow solutions and integrating into all types of enterprise middleware ( I suspect Box wants to be on this road).
2. Building an ecosystem of apps specific to a particular type of pro-user.  This is the tougher path that requires focussed acquisitions and integrations in segments like Photography, Music, Home entertainment, Managing a household, Small business ( especially restaurants and grocery business) etc. 

Spring's over and summer is here for the cloud platform's space as storage and usage patterns will coalesce to the needs of sustainable clusters of consumers and buyers. 

[[ This is a post from my Quora series of responses to questions on product management - https://www.quora.com/profile/Deepak-Alse/answers> ]]