breaking the link btwn BTC the currency, from BTC the blockchain?
The "breaking the link" is pure marketing. You may be right that it is harmful marketing try to promote the idea of breaking that link. I consider it deceptive at best.
BTC-the-currency still has all 21 million on the main chain with or without sidechains. Some may be locked, some lost, some not yet mined, but they never go anywhere. They are on the main chain ever and always.
If you've read every post here Justice nailed it with this post.
https://bitcointalk.org/index.php?topic=68655.msg9448208#msg9448208I don't for a second believe Austin Hill thinks like you do.
Never has it been said anywhere that the link between the blockchain and BTC should be broken.
What Blockstream, and Adam Hill, are proposing is to allow the
BTC to move between subchains and not be restricted to Bitcoin's blockchain features.
That is breaking the link.
They are taking the Bitcoin brand and applying it to their (and others' but I think they are more concerned with theirs) sidechain coin, which is
not Bitcoin but is another coin backed by Bitcoin held in reserve.
If Bitcoin were a defended trademark this appropriation would likely not be allowed. As a practical factual matter it is also untrue. The actual Bitcoin do not and can not leave the Bitcoin blockchain.
They may get away with it though, because as others have pointed out here, the Bitcoin-the-currency/Bitcoin-the-blockchain meme is popular and spreading.