Best case scenario if Moyes goes to Spurs, is that we install a clause to stop Spurs from taking any of our players with him, even wave compensation so they can have Round for free, and we keep our core background/youth staff and scouting network/knowledge.
Worst case scenario if he did go to Spurs, who are likely to lose Modric, possibly VDV and Bale so will be more cash-rich than usual. So will be able to fund for Fellaini, Jags, Barkley, and Rodwell who would then follow or go to another club that matches the bids. Then with Baines off to United and Cahill to the Emirates, which would leave a huge dent in our line up (quality and quantity wise), would probs have a knock on effect and scare Johnny away. Leaving us with:
Howard
Hibbert Yobo Distin Garbutt
Osman Gibson Junior Gueye
Baxter
Jelavic
Mucha, Neville, Duffy, Coleman, Wallace, Anichebe, Vellios.
Theoretically we'd have a £100 mil to rebuild, but would have difficulty of keeping as much as possible away from the bank and in the transfer fund (so basically no debt and £60 mil then). As well as the problem of keeping other players from jumping a sinking ship, especially the youngsters who we will have to rely on more heavily. But at least we would be grooming them to keep us in the league rather than out the red for a change.
This all said, I still believe we would be strong enough to stay in the league, and with the right manager and scouting network/youth development we could be back on our feet in 5 years, just in time for the return of Arteta (who will have grown 6 more legs and officially turned into a crab) and Rooney (who will have his pubes plastered to his head after running out of hair follicles on his neck).
Disclaimer: I deny all responsibility of depression or pessimism caused by this post