COnsturcgtion workers don't count as a mass gathering so they may be able to continue working on things.
It dos make you wonder how long it will take to recover. If people coming in 2-3 months cancel (I'm in for April and if they cancel rundisney I'm probably cancelling my reservation) and then they reopen are people going to immediately come back? People plan
disney vacations 6+ months out for most people so would they come in 1 month after a re-opening? Though prospect of lower crowds could be inticing.