The Russian army is railway-based and air drops are limited. Didn't work so well at that Stalingrad place, for instance.
I've been thinking a bit lately about the Kersh bridge, well that and how hot Saya Hiyama is.
It did work in Demyansk.
Big differences between Stalingrad and Crimea
1: For Stalingrad they were dropping in winter and the Germans were not exactly geared up for that level of winter, double plus so for an airfield completely cut off.
2: the Germans had to fly over Russian reoccupied clay with plenty of anti air assets, granted not nearly as good as today's stuff but still, Ukraine assets would be quite a bit to the north not right underneath
2a: The Russians were able to fight back in the air in Stalingrad, the Ukrainians don't have the air assets to contest the space. The Germans lost a lot of assets in supply.
3: The Germans were also losing airfields as time went on as their cauldron became smaller and smaller, not that they were able to bring in enough supplies before hand but still.
4: Modern Russian airlift is quite a bit better, or more accurately, the German's were shit, the JU-52 had a small capacity by modern standards as did the bombers they pressed into service.
5: Unless the Russians are beyond special needs [and I wouldn't be surprised at this point if they were] they should have built up some serious supplies. Rail can move loads of shit.
6: Not for the southern front as a whole but for Crimea at least, small land connections, doesn't need so much to hold, lowers the supply needs
7: They could move supplies by sea, yeah Ukraine have naval drones but, to use another WWII examples, Japan had human drones and it wasn't enough to wipe the seas clean.
8: For the southern front, but not so much for a Kershless Crimea only should Ukraine reach the Azov sea, there is still road transport. Yeah Russians love them the rails, but I'd hazard a guess that if they had to they can arrange to move shit by road, even if they have to take people's cars at gun point to do it,
I used to think if Ukraine reached the Azov and took out Kersh that Crimea would be FUBARed but alas I don't think so anymore. Not without a lot more help the west doesn't seem keen to supply. If they could get some serious airpower and more than 50 F-16s could supply as well as anti ship missiles it would be a different story... if the Russians are as special needs as I hope they are [point 5]