I'm an ADC main, and everything I read on the marksmen changes seem pretty good so far. However, on Reddit, there was one comment line talking about how assassins may have more time to actually kill their target before being bursted down by the ADC (around 1 to 2 seconds.......which is a VERY long time in League). However, that line ended with a comment saying "God Bless Lulu."
And that made me realize.....all these changes not only make assassins better, but also, in turn, make shielding supports better. If these changes go through......not much may change except for which support is taken. We may very well not fall into the World's Ardent meta again, but the strong scaling ADCs we have today may still stick around due to having a "get-out-of-jail-free-card" in their back pocket.
Take Janna for example. All of these changes could be indirect buffs for her, since she has notoriously been a "mid to late game support". Her laning sucks.....ALOT, but once you start getting into teamfights is where she truly starts to shine. According to the changes, ADCs will "turn on" later in the game.......right where Janna wants to be. Pair her with a Twitch or Tristana, and, well......we're right back to where we are now, just slightly later in the game.
Just my 2 cents......I guess we'll just have to wait and see.