It’s easier said than done, but it’s not that difficult. It’s mostly reconfiguration of plumbing and zone controls on HVAC. The electrical is easier to distribute.

If you commit to doing it the right way, and tear it down to the structure (but leave the facade alone), it’s not terribly difficult.

The problem is that the building owners want to do it cheap, and it won’t be cheap. It will be more economical in the long run than fully vacant building though.