if the signal is, you will have to compete for a place in this team you're not in Sunderland anymore then i think its a good thing. Plus I dont see Henderson as a long term prospect for the right wing slot he hasnt got the pace or crossing ability, his game is more naturally suited to the centre midfield position and the only reason he hasnt played there much already is he is young and suspect defensively. Gerrard was the same at his age, it was pretty clear he was a central player but he got some game time in a position with less responsibility while he learned his trade.
On the original point, a move for Johnson is good for the squad