sorry to bother you, but the only active admin in game ideas wiki AStranger195 hasn't been active for the last 10 days. and asked some of the users on game ideas wiki who wants to volunteer to be an admin/bureaucrat. i'll tell you about the decision(who will be the admins) after it will be made.
If your current admin is around to promote the user your community decides on, there's actually no need for you to inform Wikia staff about it. That'll only be necessary if you have no active bureaucrat who could promote that user. In that case, the user who is to become the new bureaucrat will need to go through the Adoption process. Good luck!
If you think Geniusguy445 won't come back even once to promote someone to take over for them, then yes - the new bureaucrat your community decides on will need to go through the adoption process I mentioned.
They shouldn't have a problem getting approved, though, if they have the community's support!