Personally, I think they should have doubled-down on letting Bruiser Sylas be a thing rather than continuing to trim down his mechanical difficulty while also keeping him an assassin. There's no way they can balance a champion with sustain, hard CC, and waveclear while also having the burst to 100-0 somebody. It's just not going to work.
The opposite direction of these changes would have honestly been better. Increase base stats, flatten his cooldowns, flatten his damage. That way, he spikes hard in the midgame, but needs to snowball in order to scale, encouraging roaming with his ult to steal as many as he can and push that advantage to finish the game early. As a bruiser, he has more flexibility to use anything from damage ults to tank ults to utility ults, since he has the tankiness to survive through every portion of a teamfight an use them. As an assassin, only a few ults are useful to him.
Maybe make a pass on AP bruiser itemization so that beefy AP champions like Sylas and Malphite can have an optimal build path that isn't full burst.