Perhaps fans on here don't appreciate the global economic impact surrounding every business. United's owners and executives would be completely irresponsible to pay or commit to pay over £100m on any player in this environment, hoever 'special' some fans think they may be. Quite rightly a pared-back budget of around £50-60m is available. Chelsea are an exception as they have cash reserves available from two previous transfer periods unspent. No other club , unless they want to run the real risk of bankrupcy will be spending more than this sort of figure. And as no-one will be spending much, the opportunities for sales is diminished as everyone who wants to buy will want to sell first.
As soon as Dortmund made it clear they ( and the player) were happy to see out another year to maximise sale value, this deal was dead. United then had to move on to evaluate options, not for one player, but for maybe two or three more reasonable purchases. This requires time. For instance purchasing Grealish would most certainly use up all of the budget, would this be sensible? It might have been for Sancho, but not necessarily for Grealish. My guess for what its worth, is that discussions are taking place about Brooks and one other attacking player. If the budget can stretch to those two, then they may well happen.
Under these circumstances, withe Smalling returning after a good year at Roma, I do not expect any defensive purchases.