Let's face it, X-wing is getting harder and harder to predict and control with every wave that gets released, and new cards may end up significantly affecting other future releases.
So far FFG's solution has been to nerf certain cards and powers into oblivion (byebye Zuckuss and Manaroo :'( ), choosing to just eliminate some of them entirely in order to free up design space.
I know that ironically, the cards I mentioned in my example where faction specific, but what brought them into the spotlight was a list made from the sum of many different parts. Dengaroo for example, used lone wolf, engines upgrade, PTL and Contracted Scouts used Deadeye, guidance chips etc.
The main excuse we hear for the rise of our new toilet seat overlords was that it was very hard to anticipate the combos that created these monstrous lists.
And this trend may continue if upgrades are cross faction. I think it would be much better to control releases in the future if upgrades are faction specific. If FFG believes an upgrade is essential to all factions, it can release a variation of it, taking into consideration that factions strengths, weaknesses and potential combos (totally random-just-to-make-a-point example: PTL for Imperials not allowing focus action, or Autothrusters for rebels costing 3).
On the one hand it may be too late to implement something like this, since there are tons of cross-faction upgrades out there already, on the other hand I 'd rather see something like this implemented from now onwards, rather than seeing upgrades getting nerfed to a point where they become borderline unusable.
Only exception to this should probably be weapons.
Edited by haritos