Personally I'd want to see locations brought back from older games but not the stages themselves. As an example, Princess Peach's Castle is more relevant today than it's ever been, having showed up in the Galaxy series, every Mario Kart since Christ-knows-when, all the starting stages of NSMB games and Mario 3D Land/World; but its design, though similar enough on a surface level, has changed pretty significantly since Melee. The same could be said about many other stages - Mute City, Green Hill Zone, Whispy Woods/Green Greens, Yoshi's Island, Hyrule Castle, Saffron City, Luigi's Mansion - they're all similar in the sense that they're some of the most iconic locations of their respective franchises but I would much prefer them to brand-new takes on these locations, not dissimilar to the way Peach's Castle was in both Smash 64 and Melee despite being two entirely different arenas.
That being said, I wouldn't mind if they released DLC packs of older Smash stages later down the line... whenever I see an old stage hacked into Brawl I'm just like "Why is Nintendo not making money off of doing this kind of thing?". Poll the fans, put their favourite 8 stages from each game into downloadable content packs, charge somewhere around ten dollars for each pack - it'd be a little bit cheeky of Nintendo but they'd make a decent sum of money off of it, and it'd keep people like us content. Win-win, amirite?
