Adding to Exceed's post, I also had an opportunity to speak with the Membership Dept today (they're only working mornings, 9:00AM -1:00PM) and they confirmed that current reserved seating will still be made available in 2021, if the $100 'Hero' option is chosen. They denied that losing reserved seat entitlements was ever club policy, but did acknowledge the email was a little bit ambiguous, and that they'd dealt with a lot of similar queries so far.
Also confirmed was the club's hope to be playing at home in front of (reduced) crowds towards the end of the season, and that if this eventuates, tickets would not be put on general sale, but offered to the membership first, presumably after sponsors and such have had first dibs.
Fingers crossed.