Apparently this was actually discussed and this did result in this design
The VK 3002 DB (might as well get it in before the wehr's do.
But apparently this idea of 'T-34 but with Made In Germany stamped on its arse' was refused for reasons of national pride.
The T-34 had a decent gun, armor and mobility but it was not a particularly good tank. It took the soviets till end 1944/early 1945 to finally fix several issues with shoddy design and production. The T-34 was good enough though and easy to mass produce.
Many seem to think that it was the T-34 which gave the Germans a nasty surprise in 1941, but it was actually the KV-1.
As for the question of the OP, unless the Germans can fix the early design flaws of the Panther and find a way to produce a lot more (and keep them moving) it is not enough to turn the tide though. It's simply a numbers game.
What would have been interesting is if the Germans had captured Leningrad and the KV-1 production line. While the KV was too slow for the type of warfare the Germans preferred, it would have been interesting if the German allies received KV tanks to reinforce their tank forces.