When a marriage ends in divorce, it is fair to call the marriage a failure even if you get a profitable settlement from the divorce and even if you both go on to better marriages. Same reason.
Speak for yourself, but the longer the tool has been around, the more I trust it. One of the chief selling points of learning something like Vim or Emacs is precisely that it isn't going to disappear next week and become abandonware (TextMate) or just lose interest from people because something else came along (Sublime Text → Atom/VS Code).
Same with a lot of developer tools. (This is sometimes bad. It is still taking a long time for people to migrate to Python 3.x, and the transition from CVS/SVN to Git and other DVCS was pretty slow.)
Why not? I wouldn't choose to develop against SaaS that I knew was going to shut down in 5 years. Parse also said they'd keep running after the buyout.