Mozilla should sell two products:
1) Storage a la iCloud
2) Payment processing a la Paypal
And for marketing purposes they should get into discovery of free/open web services, a la old school Yahoo.
As a web site builder, I don't want to have to manage credit cards. As a user, I don't want to have to trust random web sites with my credit card info. I also don't want to be redirected to Paypal, I just want a secure wallet that can be used on web sites with a drop in <paymentframe recipient="foo@bar.com" usd="8999" description="BonsaiThing Pro 1 year subscription" /> or similar.
As a web user, I want to be able to store my photos, downloads, music, documents, etc conveniently in a little cloud-synced folder. I want to be able to quickly give fine-grained access to different web apps to different parts of that space. Photo app wants to access my photos? Great. Github wants to access my repos? Fine. Photo app wants to access my repos? No.
And the discovery thing... There's a ton of free software out there. Mozilla basically has shut the door behind it. "Thanks for the install. Good luck finding other Free tools to use with it." They should be building a directory of other free software that can be used with Firefox. I should be able to use my Mozilla account to post reviews, to discuss new apps that are voted up, etc. That will allow enthusiasts to start engaging socially with the brand in a way that Mozilla (not Twitter or Apple or Facebook) can control the identities.
From there maybe there is some social identity service, but if it's just a way to engage the community—great. Like Hacker News is to YCombinator, Mozilla should provide a place for us to discuss and share web services.
If they want to get into search, that's great. Write a new shitty open source search engine that any web site can federate with. Use Google for now, but use that money to dig us out of the hole Google put us in.