So, I've done it, with 9 days membership to spare. Butterflies and auras polished off 99 Hunter yesterday, and after a bit of solo dungeoneering the daily challenge took me to 99 in the minigame too just after midnight (yes, dungeoneering is a minigame not a skill - by the same logic slayer isn't a skill ether, it's a very, very long boring quest with no reward!).
So, I tracked down Max, chose a nice black with yellow trim colour scheme for the cape, and did the huge 25-second long emote. Then I logged out, partly because I needed to go to the forums to request access to the high-level forum, but mostly because the game felt finished.
The highscores show my rank as 9,048. Normally I'd be able to say "I was the 9,048th person to get the max cape", but it doesn't quite work like that, as people who have over 99 dunge but are missing one or more of the other 99s would be on the same total level as me, or higher. Interestingly, my 346,309,663 total XP is the second lowest of any max cape owner, only Psymann (whoever he or she is) has a 2475 total with less xp than me.
This morning I logged back in. Not needing to skill any more is a very odd experience, but it frees me up to do anything I want, with no pressure. The completionist cape (even the untrimmed version) requires 120 dunge, and even if Jagex turn EoC and Runescape itself back into something I want to play, that's a ridiculous way off, even with 100k+ a day from challenges. I do have several of the tougher other requirements done, all tasks, livid farm etc, but one obvious gap is the quest cape, which requires the new TzHar quest. Despite it being very combat oriented, and also very EoC oriented, I'm giving it a go... but slowly!