I don't know whether this question belongs to SO or UX (or Programmers.SE) but here it goes.
We have built a mobile app a couple of months back, which we intend to alter in some major ways (like authentication and security) in next release. We published it to AppStore/PlayStore and it has a download count between 5k-10k range.
Now the question is;
whether if we retire our current API rightaway and show current version users a popup which forces them to update the app (via stores)
or
create a new API under a different URL and maintain both APIs at the same time (in this case should we maintain it forever or should we set up an expiration date) ?
EDIT: It'll be our first and possibly last update, since our app is a cordova based hybrid app, we intend to use silent cloud deployments without relying on app stores.