The WeDecentralise people seem to be interested in all the platforms. Although the podcasts I've heard have tended to feature one protocol, not a round-table. I'd love to hear that too.
Not come across Urbit before.
Discussion
I've seen that magazine thing before. Yes. I think it would be a make a good conference, a multi-protocol conversation conference. What with so many bridges and overlapping (and disputed) goals. As long as it didn't descend into some sort of protocol brawl lol