I agree that they would survive without the British. It is going to be interesting to see how this all unfolds.
If PZM are banning riders with a Polish License from racing in foreign leagues, then Poland could end up an all Polish League with no Brits, Swedes, Danes etc etc. Now whilst all of these riders, of course, will want to be racing in Poland, the banning of riders from racing in foreign countries can work both ways.
As has been said, a Club in Sweden has recently been closed down due to noise issues so I can see them wanting to stick with the new silencers.
Another of Speedway's very own soap operas could be unfolding!