So to sum it up:

Sure things:
-New phone(s) with Sailfish and with at least decent HW, including a nice camera
-Quite a long list of potential devices in Sony´s program
-Alien dalvik works

Still open:
-Xperia phones will only be "community devices", at first at least. So Jolla does not seem to see see them as a way to get proper revenue or to expand the user base of SFOS that much. Instead, Xperia devices appear to be 1) a showcase for their "real" customers at this point, the licensors 2) a better phone for the developers and 3) a way to "reward" the community. Not a bad situation, I would say, but it does mean that SFOS will not spread as rapidly as one might hope, compared to a situation where everyone could just buy an Xperia devices and download SFOS on it without joining some program.

Questions yet to be answered: Will there be a similar programs as with the Jolla C with a certain amount of devices with a certain timeframe when you can apply? Or are pretty much all Xperia phones "available" as community phones, buyable at will?

If there will be a same kind of program and no knowledge of the future at that point, I will probably dish out for the Xperia X next summer. If at that point it is known that the support/program will cover more devices and there is no deadline in signing up, I will probably wait a bit to make certain I can get the device I like for the next few years.