IMHO the "dipping toes" was the switch to the current model, which they did 4 or 5 years ago. It was a
clear attempt at moving from shrinkwrap to SaaS. The constant stream of reminders in-product, on blogs, twitter etc was a strong hint that they'd
really like you to pay something every few months. They were much more forceful than the average software vendor. This is why I wasn't really surprised by recent news.
As a hobbyist developer (I use PyCharm with a personal license, but I don't actually sell anything), I'm basically in the "screwed" camp. I thought it was about time for me to upgrade, but now I'll just keep using my current copy forever. I'm sad, because the tool is great; but stopping it from working when the license expires, rather than just disabling updates, is really a low blow. It signals that they don't think their upgrades are worth paying for (which in some cases is absolutely true, a lot of recently introduced PyCharm features are of no use to me whatsoever), and that they've stopped innovating and are now just rent-seeking.