It's difficult to give anything other than semi-humourous reply because - and I know this is another debate- some of us on here as far as I as I remember never agreed a blanket ban on in-season testing was a good idea in the first place. The idea was at the time that that by reducing testing costs it would place the less well-off teams on a more equal footing, and I don't think it has so far done that at all. All it's done in my opinion was to reduce the chances of truly talented drivers to get into F1 by impressing teams with their testing teams. And increase the chances of untalented drivers bringing a big budget.
I know this is a different debate but after the testing ban and its many ways of interpreting who could be given a dispensation and on what ground, something like what is happening today with Merc and Pirelli was always likely to happen at some point.