>>Can a mobile tank brigade push through to Crimea?

Into Crimea? Probably not. Look at a map. Crimea is connected to the rest of Ukraine by a relatively narrow isthmus - and the Eastern portions of it are basically swamp.

Modern tanks can withstand a lot - but not direct artillery fire. The RF has almost certainly built barriers that don't so much completely stop tanks as cause them to pause - and I'm sure they have artillery sighted in on exactly where a tank would be. This narrow passageway will be a meatgrinder for the infantry that's needed to protect the tanks. I'd expect a lot of mines, both anti-tank and anti-personnel.

There's also plenty of evidence that they've built obstacles along the water to hinder a waterborne assault.

I'm afraid it's going to have to be 1) destruction of Kerch bridge, then 2) siege.