Lyn, once Bitcoin gets a secure 2-way peg mechanism then almost any other blockchain can be a sidechain.
For this to happen we need BitVM to mature, and ideally OP_CAT enabled. 
Or wait for nostr:npub1jg552aulj07skd6e7y2hu0vl5g8nl5jvfw8jhn6jpjk0vjd0waksvl6n8n to implement Simplicity.