It would be so nice if TL could just warn us before they decide to do things like this. A fellow player had this same issue with 2 other of TL's games. She is on an older ipod which cannot be upgraded and now has lost complete access to those TL games. She had absolutely no choice in the matter as she was not able to play the games once the pop up appeared requiring her to upgrade.
Why is it so hard to just give us a heads up? People are investing real money into these games. We're not asking you to give us your trade secrets, just advance warning that you intend to do things like this.