If Felix can be pushed into playing like Greizmann, where he drops back and really can be an extra midfielder, like he did for France and did years ago at club level (to be fair, he's in his 30's), then I think Felix could be a great addition. That's really up to him and whether Conceicao knows how to push the right buttons for him.
Tomori does so much covering for Theo, for our midfielders, and for how high we press when we're playing against teams that want to hit us on the counter. I'm not willing to sacrifice him for Vlahovic--who is just so insanely expensive for what he brings.
If you're going to go for a striker that expensive, you might as well go for Sesko at that point.
I think a real striker transforms even our current team into a very different beast.