I guess if you do a lot of grinding, then it’s not for the chests anyway.
The chests are a nice little something, but I wouldn’t grind for many many hours each day and spend a lot of gems on food, just to get a chest or two more than the average “top 3 raids” player.
I mean, after all, it’s not like they’re that awesome or powerful. Yesterday I got a purple chest, and was glad I saw a legendary (golden) reward in it. Then I saw, that the reward was a legendary amount of vouchers (45 vouchers). Well, on the 60k skull chest, you are only granted to get 1 legendary reward, and that one might just as well be vouchers. Or just legendary gear that is a lot weaker than your own 20-lvls-old gear (happened to me recently as well), or just a bit of gold or bread. All of those are not worth grinding for it for ages.
So, if you get 60k skulls at all, you only/mainly did it to help your alliance. And as such, you’d probably continue past the 60k mark as well, if it is necessary to win your war (season).