If they end up cancelling the E3 (I doubt they will), then either way you would end up having to go home even if you were over here on an E3.
With the current executive order that was just signed, even green card holders that were from one of the 7 countries listed that were outside of the the US when the order was signed are now left high and dry and are now stuck outside of the US.
Given that you would be flying outside of the US for a regional, if they pulled the E3 then you would have to pack your bags and go home and lose your ability to work in the US. So rushing in now to get an E3 won't protect you in the future if they change the rules.