I think that Blizzard will not introduce any big gameplay changes. The question is what constitutes “big gameplay changes”. Some think that the screen dimension, auto-gold pickup, and shared stash represent gameplay changes. It is true. Each does affect gameplay. Are these “big” gameplay changes? I think not and apparently Blizzard does not.
I think that Blizzard does not necessarily think that these are “big” changes. Adding a charm inventory was listed as QoL as an example. The first survey asked if players were interested at D2R launch in balance changes to items/skills and personal loot instead of FFA loot. Personally, I do not want FFA loot removed. I want the option to select at game creation or character creation personal or FFA loot.
This goes back to the idea of what constitutes an authentic D2 experience. I suspect that this is not as narrowly defined as some think using the explicit staements of the lead designer Rob.
Also, Blizzard has already announced that optional changes that make the game less D2-like exist in D2R.