I'm a little surprised by the surprise, to be honest. As a few have already pointed out, this was a pretty obvious progression from the get go and... really, she's already a Mary Sue of sorts with a way too charmed life and... yeah guys - maybe it's just because pretty much all little girl shows go this way and I've grown up for what feels like a whole lifetime watching this same thing play out in all my beloved cartoon female protagonists. I mean, with all her friends just coincidentally filling the tally of Elements of Harmony magic combo team and hers being an actual freaking crown rather than a necklace - it's obvious, obvious, obvious.
I don't see them letting this be a problem though. Either she'll reject it to stay with her friends, they'll get another season or so in while that simmers and she'll be forced to step up to the plate and find some way to take them with her in some capacity - being the inner circle and elements of harmony court of the ruler type thing doesn't seem like such a bad move, or somehow her friends with automatically transition with her into some powerhouse team of ponyville that they basically are informally already.
Even with the original MLP - the ponies had to keep undergoing some stylistic changes to move the toy lines they support. That's just how these things work. Heck, I wouldn't be all too taken aback if all of the main ponies underwent some serious stylistic transformations - elements of harmony additions, royal court pony set, etc. - over the next season or two - both to come in line with Twilight's new themes as well as to generate new merchandise.