That's the technique Linux uses, it feeds keyboard and mouse timing events into one of its entropy pools. I can't see why they wouldn't do this for slot machines.
Aristocrat, Novomatic, and any other manufacturers whose PRNGs have
been cracked “would have to pull all the machines out of service
and put something else in, and they’re not going to do that.”
as long as older, compromised machines are still popular with customers,
the smart financial move for casinos is to keep using them and accept
the occasional loss to scammers.Could you prove that the extra entropy added to the PRNG pool would not change the limits? Bigger challenge: could you present it in a way that a regulator would agree with you?