The "nerf"
The base dmg of sunder at level 1 is dropped from 400+25 to 175+25.
No abillity in the game does 200 in one burst at lvl 1, so it's still the best buff secure lvl 1.
However where the nerf actually hits is with the first buff respawn, where sunder is less likely to out secure. Between levels 5 and 10 sunder will actually be far less useful after the nerfs.
The buffs
They added in pyromancer
So, pyro bomb is increased snowball potential, meaning having the best objective secure is important for not getting run over. Not to mention, pyro bomb synergizes with sunder more than it counters sunder. Because of the windup on pyro bomb you can't try to out do the secure, but if you have pyro bomb and a sunder you can leave it at 2k hp and pop sunder at the same time the bomb goes off to make effectively the best secure.
Having 2 or maybe even 3 sunders will be even more important in this patch, as there is an extra objective to contest, and not having sunder available is going to make trading objectives near impossible.
The importance of hitting lvl 10 first is going to be even greater as you can pretty much guaranteed get a snowballing objective from that advantage.
So despite the nerfs to invades, sunder is even better than before