I agree Kittle is a huge part of the Niners offense. TE is an important position, just look at both Kittle and Kelce who are game changers and need to be accounted for on the field at all times. Couple that with speedy wr's - Deebo Sanders and Hill, and you'll have mismatches somewhere. Knox has shown he can be a productive TE, but is he the mauler that can throw huge blocks one play and be speeding down the middle of the field the next play? We shall see.
To what the OP said. Need a Right Tackle (kick Ford to guard), a true #2 RB, another quality WR and our offense should get better. Not too difficult via FA and a WR deep draft.
Defense needs edge rush help, another outside LB and a true #2 CB along with improving CB and Safety depth.
Overall, we need to follow our own blueprint and not copy the "flavor of the day". Many different blueprints have won the Super Bowl - the "Greastest Show On Turf" Rams, to the balanced Giants, to the defense heavy Bucs. And of course the patsies who win with balance and an ever changing lineup.