My problem with "stable channels" is not technical, but entirely around incentives.
"A banker is someone who lends you an umbrella when it's sunny and asks for it back when it starts raining".
People want downside protection. But you cannot keep enough reserves to give it to them in Bitcoin, you need some other asset like USD, which is much harder to audit.
So in practice you offer some limit on downside protection, hopefully well-documented! But no limit on upside protection. Of course if you hit the downside limit your (broke) customers leave, so your business model is likely "hope Bitcoin goes up".
This can be extremely profitable, of course. But high-risk ventures with this kind of "heads I win tails you lose" property rarely attract the most ethical of players :(