I don't think it will be an issue, IF it ever happens.
This is how it is in Germany now, which is why all German parts are TUV approved. You fit a TUV approved part or parts, and submit the car for a TUV test. It passes, gets a certificate, end of.
If it helps get some of the badly modified and probably dangerous cars off the road, I'm all for it.
Just how many Yorkshire sheep can you fit inside one exhaust?