You could go the Ebay route and purchase not too expensive EA1's and touchscreens. If you have a lot of speaker points you could go Sonos and not worry about your OS upgrade being tied to your sound system equipment.
Control4 supports 13,500 third party products, you might be better off buying cheaper tablets with wall mounts, I/O extenders, doorbell cameras.
I get questions on my system all the time because of my touch screens. It's kind of a showcase for the product, but they will be being replaced by sheet rock now. There is no way I'm spending $1k a screen every five years, this is not an iPhone.
Bottom line, the less Control4 branded products you have the less you need to worry about swapping equipment every major OS release.