Affiliate marketing has never been stable (IMO). The most successful are those that have deep integrations with merchants/brands and know how to capitalize on opportunities and inefficiencies in the market. If you're just going to slap up a few display ads with your affiliate link and not do anything truly different/better, it's best to consider another monetization approach.
I think most online business are not stable thing changes frequently and it hard to keep track. It's not just Affiliate but everything.
When i started website development there were no smartphones and when they come out everything changed.
It's only only matter of time until something new will come out and it will change again.
Nothing is easy in life and if you are good with this subject and you earn money you should keep going with the and adjust with changes.