Hyperbole at its finest on display. Saheeli rai is not a good card on her own neither is a 1/4 for 4 mana that binks is a good card on its own when eldrazi displacer is legal. That's why I'm hesitant to say that "omg it's broken." Bg delirium is probably will really good, zombies may still be okay after losing copter, mardu vechiles got a lot of love this set, Rg energy got some love this set, and uw flash still has its hosts of good stuff cards. Sounds like a wide open format to me.
A 2 card combo that instantly wins the game in a format with barely any answers isn't broken because you can play UW Flash and BG Delirium, 2 decks which just got eviserated by bans. In fact all of the decks you mentioned were hit by bans.
Saheeli is underpowered compared to something like Liliana, but she's still a reasonable three mana planeswalker if she's both a scry engine, combo piece, and has other value cards that you can copy. The Cat blinking things is only as powerful as the things its blinking, but the fact that you can play either combo piece in either order makes the combo very resilient. You can just run out a 1/4 if you need to and untap a land or blink some card with an EtB ability, or you can play Saheeli and try to use her to accrue value. The fact that your opponent must immediately kill Saheeli, or keep up mana forever, while you just hang out and do your own thing makes the combo, just like the Twin combo was, into a significant pressure on your opponents resources even when you don't actually have the combo pieces. If you're on 5 lands, your opponent never gets to tap out because you can just go land #6, Cat, blink land, Saheeli kill you. That's stupid.