The economic incentives will only come when enough people stop buying these kinds of games. Whether or not that will ever happen remains to be seen.

Videogame preservation is on par with other media conservation, like literature; something that's an overall good for humanity as a whole, but not in the mind of the majority of consumers of such media. And that's perfectly OK. Most people just want to consume and forget.

Conservation is a social interest amd must come from organized initiatives, it will never take shape magically from individual judgement.