Reasons costs may go down:
- Even if there are only 9 branches, there will likely be less mutual exclusivity, meaning more options for combinations of SPs, so you can get more of them while still having choices to make.
- Without the "finish x branches" victory, SP acquisition no longer needs to be as limited to balance against an overly early cultural victory.
- One free SP per era sounds like a lot for a UA (however, see 2nd point below).
Reasons costs may not go down:
- SP bonuses are fairly powerful. If they were cheap too, the game might become too lopsided toward acquiring them, unless handled right.
- Without the direct "finish x branches" victory, the only benefit to SPs are the bonuses themselves. One per era needs to be enough of an edge to make Poland's UA worthy. (For similar reasons, the Oracle may need to give more SPs or a new bonus). The cheaper the SPs, the less the free ones are worth, now that they aren't directly used toward victory.
So, I don't know
Also, I think they revealed Poland's UA just to make a point about how the role of SPs is going to change a lot, since, as has been said, the UA would be extremely OP in the current game.