To break into the top 6, we need to think outside the box. The below is thinking about the next 5 years rather than the next few months, but it's what my strategy would look like.
I think we need a new style of front player. I think the game as a whole will adapt again in terms of formation and tactics, and we won't see the traditional number 9 used much in future at the top sides, unless they have a very special player e.g. Kane, Aguero.
If you think about the way Liverpool play, this is the way Everton need to look to setup in the absence of being able to spend £100m and no Champions League. It also suits Marco Silva's style, and could pave the way for Richarlison to play as the central man up top. To do this though, you need to "replace" him with another wide player, which we potentially already have in Bernard/Lookman.
Playing with a rotating 3 up top will also be better on squad numbers, making us more adaptable and less reliant on one man.