One problem I can see is that Ukraine is getting a little bit of one kind of system from one country, a little bit of a different system from another....
...and since they are advanced systems with different consumables or replacement parts, it’s going to make training and logistics very hard.
I guess NATO nations are going to find out how their legacy tanks perform in the new “drone era” of warfare, so there’s that!
Maintenance will be a headache, although a lot has been done to modularize components like engines and drivetrains so they can be shipped back and worked on in depot. There are a lot of spare parts for the Leopards in Europe for the 2300 Germany produced. Depot work might be contracted out.
Even the Germans pronounced that the tanks they can provide would be several different variants of the leopard 2. It’s gonna be a tower of babel before they get blown up.