While ACES closure was a bad news, there's a silver line after all. You see with no future version of Ms Flight Simulator in sight, addon developers can focus their effort and investment on developing in current version.

To sum it up :

“It seems that the latest version Flight Simulator X, will be the sim of choice for the next few years and so we can use this period of stability to develop more complex products, safe in the knowledge that the platform won’t be undergoing any kind of radical change.

Just Flight’s operations director Dermot Stapleton

I always feel that every new missions or airplanes make FSX feel new again, after all Ms Flight Simulator is more a platform than a final product.

via mcvuk.com.