Its a dilemma for sure. I can break away and use 2016 but it ends up being just a side thing to try the new features. When I want to get serious, I want to go back and fly the manifest I drew up for myself to build a new spacestation, and those plans require addons that just dont translate. So for me its going to be 2016 on the side, but the main girl is still 2010p1.
Not advocating my position at all, dont want to give the impression I am saying everyone should stick with 2010. The more people that use the new stuff the better for the overall health of the sim I reckon.
Well, I more wonder about features/functionality added by add-ons, not specific add-ons.
After all, if people look back, something might be missing in 2016, that 2010 had. But that does not mean that 2016 must be exactly like 2010 again and have the same add-ons. How could 2016 be better than 2010 otherwise? So, working on adding the missing functionality would be necessary, while also going ahead and not wait for specific closed source add-ons to be revived.
For example: Maybe it would be better to create an open-source "Common Vessel Base Library" middleware that unites Ummu, UCGO and other add-ons instead of using the same combination in many add-ons the whole time.
So, when the next version of Orbiter comes, only one add-on library needs to be raised to the new standard and hopefully, most of the backwards compatibility for other add-ons would be at least reduced to recompile the add-on DLL against the new middleware version.
Or having better editors for bases again, but make it easier to add content to Orbiter. The "World of 2001" is one such add-on that pretty much suffers from the more complex terrain now.
Sorry, but I am progressive and I prefer to talk about solutions instead of talking about problems...