[Zambyte]

Honestly probably a while. Selling the same game over and over with minimal changes is quite profitable (see: call of duty, fifa, etc). Selling the same game over and over again with no changes... probably more so.

[fbdab103]

Certainly working for Nintendo. Does the NES mario game require any porting effort? Yet it gets repeatedly sold on their virtual stores.

[pxx]

They might not even be using their own efforts to "port". Here's an article suggesting that they just downloaded a pirated ROM off the Internet to resell to users: https://www.eurogamer.net/did-nintendo-download-a-mario-rom-...