Dynasty Warriors: Origins had the best battle gameplay in any Musou genre game thus far, really fun game to play with some huge scale battles and a good bit of variety in the maps and scenarios.
If the DLC adds some more strategy, particularly to the world map, like a Risk board and gives the player more agency over troop numbers and such like then I'd definitely revisit it.
I'd guess the remaster will be Dynasty Warriors 4, that's the one fans tend to put on a pedestal and it's also old enough that the remaster would seem significant.