Not easy as said, how about a scenario when multiple club interested in him next season or year after that, this year we don't find much competition, having said that I wouldn't say that we should bend for whatever Dortmund demands but need to find the middle ground where both clubs happy with the trade.
Unfortunately, United is not a wise player in the market when no competition is places. As a loner we usually get robbed for tons of money, period. Not that we are noted for winning when competing with rivals for one signature, but I do believe we are able to get in better positions in negotiations. "We can do things in the market...", in a sense in which we can match almost every offer (disregarding PSG). With millions on the low for many, we can get even a better deal than the kind of the rumored one (Big chunk at first, instalements, obvious performance add ons).
What is the issue if multiple clubs are interested next season? How many clubs out there can match our financial offer? Also if Sancho doesn't want to come here when more clubs are interested, maybe it's for the better then. Stop being so insecure about it. Our position is extremely strong and Dortmund knows it. 12 months down the line with huge gate receipt losses, a lot of clubs will be reluctant to pay the transfer fee that they might even afford this year. If not then getting players which doesn't want to play here got us into this mess.
For all accounts right now, he wants to come. We are not asked 10-20m, 120m euros is huge amount, it's almost 1/5th of our revenue. No club which is self sufficient can take such decisions lightly. The amount of insecurity that is their in our fanbase is staggering. We are not some small club and even next year we will have good enough chance to land Sancho. Financial health of United is also important so that we don't stop just at getting Sancho.
If a bidwar were to unfold next summer, we could easily outbid the best offer and it will no doubt be less than this year, is not a bad piece of business, if you look at it.
Financial health signs have been coming lately, despite the obvious hit that covid means for every single actor of the football chain, freeing up funds for Sanchez salary and one to three more departures of absolut fossils to come by; rumored transfer kitty is not that miserable either.
The only delicate aspect is that we are badly starving, for so many years, for a pleyer like what we imagine Sancho can be to wear the colors of Manchester United.