Interesting ideas. With Tom Schumacher being chair of the Broadway League, the Broadway Subscription idea has probably come out of these League planning committees. Could be a nice advantage for those of us who see lots of shows each year, but it would surely require opt-ins from specific shows and theatre owners.
The "Flex Ticket" may also be a way around COVID fears. It's a way to build advance sales, and then people can decide to choose a date later when they feel comfortable. Partnered with a discount, it could be really enticing.
At the very least, it indicates what we already knew: nearly every show will have to discount and be creative if they want to have any chance of full houses when Broadway returns. And even then, it will be a tough road back.