since a minor bless no longer requires at least 4 points in a path.
No, it does. You can spend less points than that at a time, but you still need four ranks in the path to get any points.
since reinvigoration and regen will undoubtedly require those paths.
I can confirm that they do, though there are separate versions of regen for undead and for constructs that are in D and E respectively.
Hopefully it'll weaken the dominance of those blesses, probably by making them incarnate and needing your pretender to be around for them to work, or at the very least enable you to splash some other stuff on your pretender instead of being locked into EXN9. I wouldn't be surprised if, say, E5N6 or something similar got you the regen and reinvigoration you wanted, which should free up points for better scales or a handful of additional magic for another blessing. Basically something like that to make blesses less stale and/or predictable.
Regen is N8 and Reinvig is E2 (per point) currently, though of course this is subject to change during the beta.
But since national generals and scouts cost half of a mage fort-turn wise, I'd imagine that they'd see more use than right now. Giving up recruiting a mage to get two generals or scouts/assassins is a more favourable than only getting one after all. Having only 8 commanders out of 10 being a mage is still an improvement after all.
You say that, but I still see no reason why I wouldn't rather go for more mages in most situations.
How is this going to impact, say, Mictlan and other nations that can only build palisades? Or are they going to be able to build fortresses as well now to keep pace with everyone?
Those limitations are still in place. Notably, Pangaea now has a national spell (for... 35N gems? I think, this is my memory now) that builds a palisade.
With all that said... As hyped as I am for the game, I get the feeling that it's going to be to Dom 4 as 4 was to 3. Not a massive improvement or change but enough of an iteration that most people will play it instead.
I mean, isn't that what we all want though? How much more different could it be without becoming contentious?
EDIT: I found this thread with more info about the features in Dom 5. Lots of juicy details here. I'm still looking over them all.
I'd recommend taking some of that list with a grain of salt, as the thing about placing units on the walls, at the very least, is misleading.