My understanding is that they have the opportunity to sell their spots in the LCS as soon as possible. After a certain period (10 days?) Riot said they have back-up plans, but they seemed confident the spots would sell. There have been some pretty interesting trades, adds, and drops in the off-season across all regions, but this will shake up the NA LCS Summer Split for sure. Renegades were looking very good towards the end of the season, so I'm a bit more disappointed by that. TDK is also banned, so they will most likely be replaced as well.
I imagine DIG could purchase a new spot and start over if they want to since they got relegated. Apex will be a new team for Summer. TL and C9 have been creating some powerhouse Challenger teams in the off-season. NRG had some good pick-ups. Who knows what will happen? There is a ton of talent up for grabs!