They are probably doing this expecting to lose fewer than 20% of their subscribers, as that's around the figure that would still make them more money than if they kept the current pricings.
In other words, if more than 20% unsubscribe or don't renew as a result of this, that may cause them to reverse course.
If you are on a subscription that's about to expire, it could be a good idea to not renew at least for a while and see how they react.
I'm unfortunately on a year long sub that won't expire any time soon, so I can't really join in on the 'protest'.
And yeah, if this sticks, Nintendo and Microsoft will likely be considering something like this as well.