Many people forget ETH is very comfortable playing without a recognised striker. For a long time, Tadic played up front for Ten Hag. It's no surprise the club doesn't think signing a striker is a priority and would rather sign another wide player. His loss would heighten the need for one but even if he stays, I can easily see a scenario where he is phased out and leaves in January.
What should be clear, the club should not force him to stay.
Also, many people who like to mention this, forget that, in that miraculous season that basically turned ETH into a household name among football fans, Ajax had two recognized forwards in their roster: Huntelaar and Dolberg who chipped in 27 league goals and their combined starting appearances (28) are a strong indication that, when Ajax needed to play on the front foot and force the issue, ETH very much liked to have his man upfront making the right runs and opening up spaces for his wide players (mainly Ziyech and Tadic).
We, United fans, should also remember that the last time a manager of our club let his two classic forwards go (RvP and Hernandez), no matter how over the hill they both were, and chose to replace them with a winger and an inside forward (Depay and Martial), we ended up scoring 49 goals in 38 league matches. We should also keep in mind that the previous full-time manager kicked his only designated striker out of the club and put a lot of stock in the abilities of United's "golden boys" to get the team going, only to find himself fishing not once, not twice, but thrice in the pool of 30+ forwards to make his plans work.
Playing without a man in the box is one of the toughest tactics a football manager can pull off. It requires a lot of forward planning and a great understanding of each player's strengths and weaknesses. Because if you feck up and there's no contingency plan for where the goals are going to come from, what you'll end up with is playing week in-week out against a relaxed back-four that'll keep its shape and let your attackers hit one brick wall after the other. I'm not arguing that it shouldn't be in the cards under ETH's tenure. But it would be surprising, if he chose it without even spending 6 months/1 year with the squad. Surprising, not in a good way. And what the club thinks, is more scary than reassuring lately. I wouldn't trust them to find a prayer in the bible, let alone plan for us to play like peak Barcelona.