And there might be other procedural techniques that the UK gov't might try to push the current longterm ILR-holders out of that status into citizenship. Right now, if you have ILR you don't have to renew it or whatever. You can access benefits or travel in and out of the country using your current passport and your previous, expired passport with the ILR stamp in it if you wanted to.
The UK gov't could force a renewal regime on ILR holders. I don't know, maybe even introduce certain tests upon renewal as well. They might say you have to renew the status or the proof of that status every two, five or ten years or when your current passport expires. I don't know. Pure speculation. But it has been done before. Proof of right of abode, for instance, used to be permanent. But a couple of years ago, the proof of the status (not the status itself, in this case) became limited to the validity of your passport. Now you have to renew the proof of RoA when your passport expires for a hefty fee. There might be precedent in that for ILR. Just a thought.
Edited to correct word error.
