I recall I wrote about it in this thread back in the day, but I lost much of my sympathy for Umtiti even before his entire pathetic handling of his knee injury pre-2018 World Cup. Mainly due to how he behaved (in public) before the club decided to extend his contract.
Ever since that chronic knee injury he has looked done and dusted. Might as well part ways with him next summer or at least as soon as possible, even for peanuts, considering the fact that we bought him for a cheap price and that nobody is ever going to pay a lot of money for a crook with a dubious attitude and decision-making.
While de Ligt is a promising CB talent, I would prefer a CB like Konaté over him every day of the week and the CB position is generally a stacked position nowadays and tons of new promising CB are emerging each season. So not really worried about that position long-term as long as the clueless board (which is another problem) manages to replace Piqué and Umtiti adequately.
For starters giving Todibo a chance to prove himself and buying a Konaté level talent and potentially a finished product to replace one of Piqué or Umtti (if needed), would be the right thing to do.