The first step to recovery is admitting that you have a problem. Unfortunately the appointment of Rangnik could be Utd doing just that, rather than desperately clinging onto the past and thinking that they were 'a couple of players away' from being back to their best. The longer Woodward and Ferguson called the shots and continued to promote unqualified ex-players as managers and coaches, the longer their demise was going to last. So although the appointment of Rangnik by itself doesn't mean that they have actually turned a corner this time, it is maybe a worrying sign that they have finally learned the lessons from the last 10 years of mistakes. Klopp said it best himself when he talked about having to write our own history, whereas Solskjaer and co were desperately clinging onto the past and trying to recreate it.
The job he faces is huge though. Klopp is a genius but he was also brilliantly backed up by a recruitment team that basically batted 1.000 for 4 or 5 years. The fact that the CL and PL winning team only had Henderson, Milner, and Firmino remaining from the squad that he inherited (along with Lovren, Lallana, and Origi as squad players and Gomez and TAA from the youth ranks) is testament to just how much change happened in a short time. I think that Utd need just as much change to compete at that level as well. Sancho, Rashford, Greenwood, Varane, and maybe Van der Beek, Shaw, and Fernandes could be long term pieces of a successful squad, but beyond that you are looking at outright dross, aging players, and overhyped players who likely don't fit in a team that wants to play expansive possession based football.
I always laughed when pundits talked about improvement and progression for Utd when they had finished 6th (66 points), 3rd (66 points), and 2nd (74 points) as if the finishing positions were all that mattered and so they only needed to improve 'one place more'. The reality was that in style of play, underlying stats, and points total there really hadn't been much improvement at all, and the gap between 74 points and the 90+ that you need to realistically win the league in the current era is a chasm rather than a gap. Better players can gain you extra points, but wholesale systemic changes were clearly needed to take the club to that next level.
Klopp and Guardiola will likely be gone in 3 years time, and no doubt Chelsea will have fallen out with Tuchel and be on the downward part of their constant boom and bust cycle, so there is a ray of light at the end of the tunnel for Utd and also the possibility that we'll see a dip back to mid-80s point totals being good enough for the title. It will be interesting if they can actually play the long game this time, or whether another shiny gem like the Ronaldo signing will come along to distract them and derail the whole process again. Here's hoping for the latter!