WDW has not yet cancelled June stays, but they have frozen June stays so you cannot make additional June reservations nor modify current reservations. I think there are two plausible reasons:
1. They are fairly certain they are not opening in June and will continue the rolling cancellations. In the meantime, they are freezing new reservations.
2. They are optimistic they are opening in June, but the opening will be limited (consistent with modification rumors). Freezing current reservations allows them to assess the number of guests that they can allow entry. The reopening may also have very limited or no TS dining and limited or no ADRs, and that is why they are not allowing new ADRs.
There will be two important clues coming within the next 5 days:
1. The CM schedule update - The next one was supposed to be out this morning and is delayed. If we see schedules for late May, we can expect that WDW is ramping up preparation to reopen. If we do not, I would seriously doubt a June 1st opening.
2. Rolling cancellations - The rolling cancellations typically start happening on Thursday afternoons. If we see cancellations for June 1st on Thursday, well, that pretty much will tell us we won't see an opening soon.