What do you feel about ditching Steam for GOG?

Nope. Steam has very good support for GNU/Linux. Maybe when GOG client also has it I would think about it.

I'd never switch from Steam to GOG, because I really enjoy Steam's Remote Play feature.

I was deeply troubled with the fact that Steam does not really offer any options to get older games running on very capable computers, and with them stopping Windows 7/8 support early this year, and Windows 10 support going away in a year, people will add their computers to the landfill soon.

However, being able to run old applications and games, whether from Archive.org or GOG.com could prevent it. Even an ESR version coming from Valve could really help mitigate this issue.

How do you think people could prevent/slow down this disaster from happening?

I am fine with valve and have more of a grudge with Projekt Red and the abuse of their employees in Poland. So I wouldn't.