Exo almost certainly will be up there with Suju, BB and TVXQ. Maybe add in someoneike Winner or maybe even BTS (quite a bit of hype about them for still a relatively new and from a smaller label).
For girls, well that's the hard one, i don't think any gg is gonna be anywhere near SNSD; we've already got groups like 2ne1, Sistar, T-ara, fx, Apink (ok they're still a bit new) and none of them spearheaded hallyu as SNSD did who are on the same level as the hallyu boy groups i mentioned above.