Will definitely give D4 a try just out of respect for the franchise.
D3 died for me shortly after they removed the AH. I get why it was done but for me, D2 had its staying power and commitment from players because of the on-going strong market and trading communities. Hoping for less account-bound items and more trading or else it'll just be D2R for me.

Don't have the most confidence in the development team though since there weren't significant changes to the team that built D3. Model after WOW and not repeat D3 please!