I played 5 games today and only saw 1 mage

You can check my match history. It was Ahri mid who is really more an assasin any way. 49 out of 50 where either AD champs, resourcesless champs or tanks. Every game was an arms race to see who could one shot the other first. I am really worried about the future. From what I am seeing on the PBE adc's will reach their powerspike with 3 items instead of 2 as it is now. Their early to midgame is a bit weaker but they got compensated with an even better lategame.

The problem I am foreseeing is what I have experienced during season 6 with Sated Devourer. If you picked a sated devourer champ you put so much pressure on the enemy team to close the game fast to prevent you from scaling that they had to take risks. Any other lategame champ was invalidated by sated devourer. What we saw was people not playing to win for the first 15 minutes but playing to stall and it became an inevitable lategame scaling instead. That is my main issue with especially the Last Whisper changes. That adc's and assasins like Zed will reach an inevitable lategame where teamfights won't last 3 seconds because tanks can't actually tank any more.

Inevitable means that you can't close out the game fast enough or their early game isn't bad enough to justify their scaling. Either way the pressure is on the enemy team who are almost playing a lose-lose situation where they are forced to take risks and therefore might also lose the early game or not take risks and definitely lose the scaling game. Going even in early to midgame is not enough, you must win hard to close the game.