Classic zombies could work as long as make it more about the numbers and scenario in which you encounter them. Once RE2 hit it became far too easy to escape them. Being able to push them off pretty much ruined them. In the original if you got cornered by a bunch of them you were pretty much a goner which is how it should be. RE3 at least threw enough of them at you and increased their speed. Revelations could have easily worked with classic zombies especially with the changes it made to the dodge function.
Current RE isn't really any less like classic RE than DR is at this point. Just make them much harder to kill, restrict the ammo(not really a problem exclusive to current RE by any stretch) and make sure understanding enemy patterns/placement and juking are a useful skill again and DR-ish numbers could work.
That's more like it. You'd need new protagonists too. Although old school zombies simply wouldn't be that hard to kill with the current gameplay and there is no way CAPCOM would return to the age of fixed camera angles and tank controls, which are what kept a lot of people away from the series in the first place.
One shot to the head is all it takes to kill zombies, and I can't see them giving them Ganado/Majini levels of resilience (even though, story-wise, those are as vulnerable as regular people). Even the ones in Dead Rising aren't very strong, it keeps the one-shot kill, and makes it so that one hit with a plank of wood is enough to kill them.
Also, the t-Virus is simply not a threat in the Resident Evil world anymore. So you'd need a way around that.
A game where you play as some villager in a somewhat large but poor, underdeveloped area suddenly hit with a t-Virus outbreak would be cool. No weapons for the most part but you'd probably find the occasional revolver with a few bullets you have to use wisely.
