I'm particularly concerned about the prospect of Mickey and Minnie's Runaway Railway never coming to Disneyland at all, given the circumstances. I mean, yes, they would have to finish Avengers Campus and that emergency stairway over by Space Mountain, since they are half-finished, but what about beyond those? Depending on when Disneyland opens again (I have no idea), it could definitely be much, much longer than the allotted 2022 opening year for Runaway Railway.
Why would this suddenly be cancelled? They already started the work and spending the money. And we know attendance will probably be soft for awhile whenever it does open back up. History seems to show that projects gets on the board faster when attendance hits slower peaks, not less. But yes it could be delayed since we have no idea when work will start again as I imagine Avengers Campus will be.