Context, most likely. That's Pompidous underwear you've got there. How many Pompidous are there? Most of the time, the sentence itself should tell you whether the s is for a plural or for posession. I'm sure there'd be kinks to work out, as there are with any change. Think of it this way though: how many horribly written posts here do we decypher on a daily basis? The mind can make sense of even the most horribly written statement. In many cases, apostrophes aren't the only punctuation in short supply. I'm not a fan of the idea of removing even more punctuation from written language, but if it's going to be, I'll cope.