Unfortunately there doesn't seem to be anything in the CBA yet about this, so I would assume real life NHL rules will have to be honored for now. The most up-to-date info I can find is that CHLers need to be signed within 2 years (as everyone knows). For college players, they basically have up to 4 years to be signed, but there seems to be caveats where the older they are when drafted the time limit shrinks. Players drafted from European countries with NHL transfer agreements have 4 years to sign. Players from countries without transfer agreements (i.e. Russian currently, as the transfer agreement was suspended after Ukraine invasion), rights will be retained indefinitely. But I'm assuming players drafted while the KHL transfer agreement was in place will still be subject to the 4 year window.