I think we could have faster progress if we could implement new protocols without the legacy baggage of providing backwards compatibility. Just don't think that

I think we could have faster progress if we could implement new protocols without the legacy baggage of providing backwards compatibility. Just don't think that works for email. Offering a side-by-side option is interesting. I think that might achieve the best of both worlds. I wonder how much extra engineering work and complexity that adds, if any. It might actually be lower in the long run.