Even though I am a 99% retired player, I'll chime in as one of the likely few owners of a rare minipet that didn't RMT or bot it and has seen this update. I've owned my Island Guardian (Fern for those of you who have not met him) for probably 10 years now. That means I've had 10 years more to play with my Island Guardian than you have with yours. We've been on adventures all over Tyria, Cantha, Elona, and the North.
Turning to the market for rare minis. I can only assume that last month, there was probably 20 buyers willing to throw away some stupid number of botted or RMT'ed armbraces or dollars for a Mini IG/Panda/Kanaxai/MKG for every 1 owner. And how many owners were selling them? Maybe a couple. But how many people who obtained the minis without RMT or botting were selling theirs? Probably zero. I don't see how this math has changed. Maybe short term, there will be a couple RMT'ers who are hitting the panic sell button, just like people did last week in the stock market. But once all that weak money is flushed out of the system and things stabilize, the supply side of the curve for these minis in tradeable form is going to be similar. There was no reason last month for anyone who owns a Mini IG/Panda/Kanaxai/MKG to sell it. There still isn't this week. Especially given that nothing was done to kill the underlying problem of botting and RMT which is driving the hyperinflation in this game.
Looking to the future. I hope if this update did one thing other than make some people happy, it introduces a little bit of nervousness into RMT'ers that any time your "investment" principle can be at risk. I await some day in the future when this same thing happens to rare tonics and weapons. I see no reason Anet keeps EL Reindeer tonics exclusive when they can add a quest over Wintersday and award an untradeable EL Reindeer tonic at the end. Or create a chest that drops any OS weapon skin at the end of some quest... I think I've heard of a similar chest before ;).
Happy travels. And remember, Guild Wars is a game. It's not real life. Guild Wars items are not investments.