It says "the recipient can use this under GPL v2 or any later version as published by the FSF", which means if they recipient is happy with the rights they got under GPL v2 they can keep using it under that version for as long as they like.
The only person agreeing to future license changes is the publisher of the code, and they're the ones that chose to publish it under "GPLv2+" or whatever.
If the FSF goes rogue and changes the GPL to be incredibly restrictive (i.e., allowing proprietary redistribution, and I realise this can be considered permissive..) it might be possible to get it to be ruled invalid defaulting to the more permissive licence, especially if you have deep pockets, or if the FSF change the licence to be ridiculously permissive like 0BSD then it's not going to be legal in countries like Germany, either way any major change is likely to result in an international enforcement nightmare.
The scenario where FSF goes "rogue" would be if gplv4 became more permissive, e.g. if it stopped being a copyleft licence.
“You can do A, B, and C with the software I wrote, or whatever X may at some future date decide you can do with it” isn’t something everybody is happy with. It certainly requires some long-term trust in what X will or will not do.
The GPL 3 is a pretty benign improvement on the GPL 2 (though I know Linus objects to the Tivo clause). I don't think anyone who was happy with their software being used under the terms of GPL 2 would be unhappy with it being used under the terms of the GPL 3 additionally, rather than exclusively.
But let's imagine the next version of GPL 4 was "Additionally the authors may at their discretion use it under the terms of the CC-BY-SA license". Nothing wrong with it as a license, but that's a bigger leap in terms of license changes.
It's not hypothetical that they could exercise that kind of power - they _did_ with the GFDL with the "wikipedia can relicense as CC-BY-SA" clause in GFDL 1.3.
I think most people would agree that that was a responsible use of that power. but I can understand those that don't want to extend the trust that all future uses will be responsible.