The owners/architect will try to incorporate to door into the new building. They point out that it is not a fire-rated door and could only be used architecturally, perhaps someplace in the lobby. Hardware may also be an issue. If they can't use it, they'll let us know and hopefully make it available for someone else's use.
Re-use of old an structure is never easy and always more expensive than you think it will be. The owners of 210 Main will confirm. There are no instructions, warranties, or guarantees when you marry old construction with new. This couple in the UK
managed to do it with an old theater but went over-budget by 100k pounds (from 350k to 450k).
I realize we are just talking about a door here but you get the idea.