There are experts who are looking at Russian attrition and say they will be done by June. I won't make any bets. In the favor of these experts there is a point where the differential equations for modeling of combat (Lanchester) break. The point where the Regular Iraqi Army after being smashed by airpower for a month lose their ability to stand and fight and the Republican Guard do stand and fight at 73 Eastings and get destroyed by the US Army who are happy not to have to fight all those non-Republican Guard units to get to the RG. Another example is the German Army in Normandy after fighting hard in Normandy for a month+ in June/July 1944 finally broke and were nearly encircled. The difference besides our numbers was our firepower.
I look at the situation in Ukraine and I don't know how the Ukrainians actually reconquer all of the lost territory unless they just keep killing Russians. Killing Russians requires accurate artillery or other long range fires (drones, missiles, airpower). Their ability to go on offense thus far as been driven by the Russians withdrawing from territory to consolidate their forces because of attrition.
So, more US and western artillery systems will give them that ability to smash the Russians and win.
Am I optimistic this happens by mid-summer...nah. Russia is a big place and it has a lot of resources. It might break but the most Ukraine can hope for is they cry uncle unless Putin dies.