Yes; exactly this. I'm contracted to Google, and so much of my Googler colleagues' time has been wasted in the last year porting projects off of the Python 2 APIs which are about to be shut down.

Are they porting to the AppEngine Python 3 APIs? Hell no: those are totally useless (no BigTable, no user authentication, etc.). If you have to rewrite everything to replace all the functionality that used to be "batteries included", you might as well build something can run on any old bare VM instead, and so—like any sensible external developer—my colleagues are doing everything they can to avoid depending on any Google-specific APIs, libraries or platforms.

I really though AppEngine and PaaS were the future, but evidently that future will not be written at Google.