Ex-Wales centre Watkins, who arrived last week from Gloucester, will miss the start of the new campaign following a hip operation in June.
And Dragons regular Rhodri Gomer-Davies is also recovering from ankle surgery with little more than three weeks to go before the Magners League kick-off.
The Rodney Parade-based region have already lost three-quarters Rory Sidey, Marc Stcherbina and Gareth Maule this summer.
Australian Sidey has returned Down Under to join Super 14 outfit New South Wales Waratahs. Stcherbina has retired following a serious back injury last season while Maule has moved to Welsh rivals the Scarlets.
That has opened the door for Newport’s Tom Riley to step into the squad, having made a handful of regional appearances for the Blues. Academy player Adam Hughes is also considered to be highly promising.
