They recorded more than 20 shows of the On Every Street tour, they can do whatever they want
If they only wanted, they could do great things...
Just imagine a "dire straits 40th anniversary edition"... they could had release it with plenty of bonus, like the honky tonk demos, the rest of demos including unreleased songs like "real girl" or "eastbound train", the London Paris Theatre concert, the Rotterdam 78 concert, the Paris Chorus tv dvd... That only with material we know exists, it's so likely that exists more than we don't know...
They could release any single DS cd with tons of great material...
But they don´t give a damn about it.