Caporegime
If you think Utd will be in a position to challenge at the top of the table by making 2-4 signings then you need a lie down Shami. The spine of this Utd side/squad will not be the spine of the next Utd squad/side that wins a major trophy. Before Utd are in a position to challenge for major honours you will have changed most of the squad. Not only are most of your squad not good enough, they're completely unsuited to playing under this manager.
The above was not the case at City. The spine of the City side that won the first title under Pep was there before him. They made a number of incremental improvements in a few positions around that spine but other than the keeper, there wasn't a fundamental change at City.
They spent 450m on players and the only fundamental change was the keeper? That is impressive. The rest of your post...I have no idea what you're even responding to because you just made one hell of a strawman.