Also concerning Eviolite Sableye... it beats the spinners of today, sure. But who's to say we won't get another way to Spin that knocks that little shadow imp flat? Gen. VI will probably be an entirely different metagame, so there's no guarantee that what works well today will work at all in October.
For one matter, like I said earlier, it doesn't beat just spinners. It can check the majority of Terrakions currently (I highly doubt it'll change much with the gen transition, and if anything it'll be a la Metagross where the metagame is less kind to him. Unless there's a new DW and Terrakion gets a new ability that's awesome, but considering that he didn't get a new ability under the current DW, that seems unlikely), and the mons mentioned previously. Also, we'll be lucky to see one new spinner. Rapid Spin is somewhat of a niche move flavor wise, very hard to justify giving to a pokemon. Very few designs could concievably do it, and since GF doesn't care about the competetive enviroment, we'll be lucky to see one sub par pokemon with Rapid Spin, much less an OU viable one.
And, I notice a lot of times that when someone brings up something that'd be good in the current metagame, you say that there's no gurantee it'll be good in the next one. But, there are several pokemon (Starmie, Salamence, Magnezone) who
have successfully transfered between gens without sucking. And, in some cases, they didn't even change that much, if at all. Yeah, if we're talking about Gen 5 -> 2, it'll be vastly different. However, the last huge shift in metagame was 1 -> 2. Each of the metagames, other than 1 -> 2, is somewhat similar to the one before it. Plenty of GS threats survived into RSE, RSE 'mons survived into DP, and DP into BW. While a lot of GS threats aren't around anymore, it took most of them three metagames to fall out of style. Nobodies expecting the metagame to be indentical, but it
will have similarities. GF hasn't shaken up Pokemon that much since Gen 2, it's always gradual change, so we can expect a lot of the same stuff to apply, even if it isn't everything. So, since Evo Sableye checks several current threats, it will remain good assuming these threats stay around. Considering that Eviolite Sableye checks any physical attacker that isn't doing 70%+ in one attack, it's a fair assumption that it will stay good.