Unless it's banned, the others will probably all have something similar on by Barcelona in May - but it's a very expensive thing for a small gain.
It means new rear-wing endplates and tubes in the beam wing and through the car, plus lots of new rear-wing endplates. You're looking at £150-200,000 to develop it.
And all the others will have to move their DRS actuation system. On the Mercedes it's in the rear-wing endplates, which is what allows them to have the hole, which otherwise is illegal. The others all have theirs in the centre of the wing.
I'm not sure they get that much advantage out of it.
Their straight line speed is not as good as the McLaren, which has the same engine and the car is not as consistent.
If it did really work well you might get 0.1-0.2secs a lap, which is a lot of time, but how much engineering has gone in to get that to work, and is it always helping you?
Those are the questions that will be asked.