IMHO, you just cannot cut the tank evolution like that. Development of T-34 was a process that started with BT-1. Its development was married to Soviet doctrine and something along the lines of T-34 will be developed.
Ok then. But could delaying its development be possible? (as opposed to removing from the face of history completely)
Well, possible. Have comrade Koshkin get Stalin cross and it would retard the development of T-34. For how long remains speculation.
Maybe have them persist with the multi-turreted monstrosities such as the T35 and T100?
Really though, I think a T34 analogue is inevitable as the war progresses. A cheap and fast tank to produce, well protected and well armed, whilst still fast and reliable - very much a product of lessons learned.
An interesting AH might be a reverse lend lease of a few hundred T34 to the UK...
If the T-34 is rejected, the T-50 will probably be accepted for service.
Or maybe the A-20?
The T-34 project was only one among many in Soviet tank development, as you can see from my links. The main Soviet tank will probably carry the 45mm gun longer, and perhaps be a bit lighter, but otherwise I don't see much difference.