I do not think it is revenue Microsoft is afraid of losing, it is the money for having to forcibly buy back perpetual licences from current GP users. If this was about revenue preservation the drumbeat around "upgrading" to a product that is not superior would not be so strong.

Tricking customers into upgrades relieves their contractual obligations. Apparently so does stepping up the update cycle (when not much of value is being improved). Microsoft is working to reduce the active install base of GP to reduce the eventual licence buyouts.

My advise, hang on to GP as long as you can. It works, it plays with useful reporting tools, it is controllable and safe, and best of all if it is killed you get paid. Upset Microsoft and keep up with the updates.