Is there a way to load regular DS roms through some sort of homebrew application?

 

Not now or any time in the near future most likely, I won't say never because, well, look at what happened with nintendont, but that was like a decade after the wii launched, so, yeah. I guess the short answer would be no.

 

The Wii was already fading out in sales and stores cause the Wii-U took over, now 2 years later we see a descent piece of software on Wii and Wii-u to run backup Gamecube iso's from external hdd (you could earlier with othe rmethodes)
So basicly Nintendont lets you play Gamecube iso's from external hdd on Wii and Wii-U (in vWii)

 

Not happening, unless there is some major modifications done to a few different firmwares (Maybe not even then).