Nah. Skarmory simply isn’t as good as Ferrothorn and completely deserves to remain one subrank below it. There are 2 main reasons for this.
Firstly, the obvious fact that Skarmory is just way more passive than Ferrothorn. Ferro’s Gyro Ball and Power Whip both hit pretty hard and can be kinda tricky to switch into. Skarmory, on the other hand, usually runs Iron Head as its only offensive move, and the fact that it doesn’t even 2HKO Mega Alakazam pretty much tells you all you need to know about it. Sure, it can run Brave Bird, but the recoil from it can become a real problem, and you need to sacrifice either Whirlwind or Taunt, which, if anything, makes it even more passive. This leads it to get overwhelmed much more easily, and severely limits how much it outlast its switchins.
Speaking of which, another thing Skarmory lacks is a good way to wear down its checks. Ferrothorn’s Leech Seed can cripple pretty much any switchin bar MVenu and really helps it stay alive throughout the battle without giving free turns to dangerous stuff, all the while helping out teammates with the passive recovery. Skarmory, on the other hand, doesn’t have a move nearly as spammable as Leech Seed, Whirlwind requires hazards in the first place to wear down stuff,Toxic isn’t nearly as good in it since Heatran still comes in on you, and you lose the ability to stop things like SD Scizor and Bisharp which, once again Ferrothorn can wear down way more easily.
These two factors mean that, unlike Ferrothorn, Skarmory struggles to do more than pure supporting, and if the opponent still has a Defogger or Spinner active, Ferrothorn has much more potential to actually do things than Skarmory. Ferro also has other advantages over Skarm such as higher overall bulk, which, combined with its higher power, makes it much better in neutral matchups and last-ditch scenarios, Iron Barbs which enable it to wear down checks much more easily, and access to Thunder Wave which is a much more permanent answer to setup sweepers than Whirlwind.
Overall, despite Skarmory’s Ground immunity, reliable recovery, access Whirlwind, Defog and Taunt, and lack of a 4x weakness, it is simply not as effective and nowhere near as difficult to deal with as Ferrothorn, mainly due to the fact that it cannot pressure the opposing team or outlast its checks anywhere near as much. It may be just as if not more splashable than Ferrothorn, but in practice, it's far more of a momentum drain and simply doesn’t pull its weight as often as an A+ rank should.