https://www.fantasyflightgames.com/en/news/2016/6/3/2016-world-championships-registration-primer/

Were Regional byes allowed last year?

I'm surprised at the lack of reaction to this given last year's catastrophe over many not being able to register.

No thoughts at all about the changes to enrollment for this year?

The byes aren't technically allowed as byes, they just reserve your seat. They did that last year as well.

The new system seems reasonable. I'm curious to see what the schedule is, I hope X-wing is closer to the weekend this year.

I don't see anything about regional byes. Winning a regional (US/Canada) gives you guaranteed entry, but I don't think you get to use your bye.

They need to release nationals prizes