English Cups don't do "home-away 2-game series" unless it's semis', in FA Cup you also do if you draw but that doesn't matter. I guess if you do consider some sort of a knockout bracket in NHL scene, a some sort of a system of byes should be involved that will ensure clubs of Pro and Elite enter the competition at later stages which also means that there won't be no seeding, the match-ups in each round would be determined by a random draw. Not too sure about how exactly the match-ups could be played out. Could be a simple BO3... there is no such thing as BO2 unless you want to introduce aggregate like in CHL which will allow draws. 😆
Bit nutty but not a bad concept imo.