I'm glad to see that there are a few more positive responses now. Before Adam posted, it seemed like everybody except Andrew had something negative to say about WordPress.com's support. In my experience, WP.com provides the best support of any free blogging service. The active forums and quick-replying staff are a testament to that.
Returning to the topic, for the past two days, I've begun trying out different CSS attributes to see which ones are likely to be abused and stripped out. I asked for help from one of my friends, who's more skilled at using CSS than I am, and he sent me some code that he found on a site that teaches people how to use inline CSS on WP.com. Surprisingly, I found the code to all be pretty unastounding. The only attribute I found that normal people would probably not need to use inline is
The rest all seem to do pretty basic stuff: making text bigger and smaller, changing their font and color, adding a space above some text, wrapping text around the sides of pictures... They're code that aren't likely to be candidates for being stripped out. Maybe it's because I'm don't use that much inline CSS anyway, or that don't know how to use it in a "tricky" manner, but these attributes seem to do only basic, unremarkable stuff that can't be used to alter the themes. There don't seem, to me at least, to be many ways to abuse them. So maybe the upcoming changes aren't going to be as big of a deal as I thought, since few attributes seem worthy of removal.
Until we get some more definitive answers about what will stay and go, I'm curious to hear what code other people think are being used to get around the CSS restrictions. Maybe in the mean time, we can develop our own list of candidates that will likely be stripped out in the upcoming changes.
Thank you, tellyworth, for sharing what you know. It's good to see some confirmation that the basic styling attributes will likely remain, which is pretty much what I concluded from my experimentation with that sort of code.
I agree with Andrew and Adam that some of the "abuse" is likely coming from users who are trying to bend the rules and find ways to use the custom CSS features without paying for it. Maybe those users aren't aware that this hurts WP.com, both financially and by creating a community of haves-and-have-nots using unscrupulous means. But, I think I might know of the physically malicious, damaging uses that tellyworth is mentioning. It might have to do with the two attributes I've previously highlighted for removal, and possibly a third. Like tellyworth and Adam have said, it's probably not wise to talk about it here, in case somebody tries to have some "fun" before the changes go into place.