As far as old consoles go, I'd rather not hunt down an old cartridge, be it by buying it through the Virtual Console or downloading a ROM and playing on an emulator. It's more cost effective, it's more space effective (I've really been struggling in terms of space for games lately), and it lasts longer.
The big exception is PS1 games which have horrible emulators (any emulator that doesn't just automatically run is horrible) and, quite frankly, I don't have access to, say, the Playstation Network Store or whatever it is to get classic PS1 games, so I'm forced to hunt down the discs.
As far as the return to cartridges go, I would love that. Cartridges are so durable, whereas discs will die at the faintest of scratches. And cartridges only die when it gets pounded into a fine paste. Less space efficient, but still, durability > storage in my opinion.