Vayne's dominance is mostly due to superior itemization, not the meta picks.

Vayne has always seen a fair amount of play in every meta, as similar to Lee Sin she makes flashy plays and feels strong, even when she isn't statistically. Its no surprise that she's become incredibly dominant when she actually is strong.

However, people are attributing her strength from coming strictly from the tank meta, even though I've seen tank meta's multiple times over the years, and never saw a spike in Vayne win/play rates. Really, Vayne's strong % AD steroid on Q, Strong flat AD steroid on ult, and incredable self peel with q and e make her one of the best AD's against squishes as well - Vayne's kit is equally effective in assassin meta's as well.

The real changes that have driven her over the edge are Itemization - She is the only ADC that prioritizes Bork and PD, two items that have been substantially buffed in itemization and effectiveness, while all other ADC's have received nerfs to their one and two item effectiveness. The shifting on 5% crit from IE to PD made IE considerably worse for most ADC's, but its still a priority over PD as crit needs AD to be effective - Something that Vayne gets for free on her ult. Bork has been pretty consistently buffed this season, both in effect and build path, and together these have removed Vayne's historical early game weakness due to poor itemization. Win rate by game length shows that she has a strong early game (51.44% in games less than 25 minutes in platinum and above ranked games), decent mid game as the other ADC begins to complete multiple items (49.87% win rate in games 25-30 minutes) and great late game from then on.

Although I honestly don't think Vayne is that overpowered right now, she is too reliably strong right now without meaningful weaknesses - most of the standard ADC weakness (squishy, team dependent, easy to catch and kill by assassins) are largely negated by her kit, and while her siege is somewhat sub par, many other ADC share that to a similar degree. I'm mostly just tired of seeing her and jinx in every game.

One thing that I'd like to see, even though its not really a nerf, is her condemn changed to 550 range edge-to-edge so it exactly matches her auto-attack range to clarify its play.