He'll be on the field for ND in the fall is the simplest answer.
To begin with, the reason he opted for another year in college was primarily because there are major questions about his fit in the pro game. He was unlikely to get drafted based on his work at WF.
Given that the BG game is April 22 and the NFL draft begins April 27, there isn't any time for him to try out for the pros and the fact that he would have gotten beaten out by Buchner wouldn't be a great indicator. Could he get signed as a free agent? Sure but to what end? He clearly needs to show off some NFL skills and it isn't as if he will get much of a chance as a FA QB in a pro camp.
If he ends up as #2 to Buchner, then he doesn't have a pro future anyway, now does he? If he wants to play his best option is to go into the portal to hook up with another college but that is fraught with its own set of question marks.