Undead survived for years and years with conversion-only elites. They're just being returned to being the race for very active players who like to attack all the time.
Worried about not being able to go into war with full elites or massively pumped offense? You're not meant to anymore. Go in with mostly offspecs and convert your way to amazing offensive growth, you will be the attacker whose offense actually grows well without any effort during war. If you want big offense right when you go into war, play an Orc.
Worried about getting landfat while you try to convert elites OOW? Hit into Fortified kingdoms, you gain half the land but still get full conversion rates.
Worried about not being retal'd when you attack for land to convert OOW? Run semi-suicide OOW and make it easier for the enemy, then just pump defspecs to reasonable numbers once war is looming. Specs are very easy to train up in a pinch.
Worried about being retal'd with Learns later in the age when you attack for land to convert OOW? Run some Schools OOW while you're trad marching for conversions. Holy crap, a building that protects science! Where did that come from?!
Worried about having to get intra-razed to stay small instead of growing fat with land while trying to convert? Make friends outside your kingdom. Be social with other players, ask for a raze if you need one. Heck, be social with other undead! Trade land grabs for razes, back and forth. Your kingdom isn't responsible for your personal inability to play the race you chose effectively.
Can't handle the new (old) undead playstyle? Play another race.
Still want to play undead? Adapt properly and continue to thrive.