The timing never really matched up. There was always chatter about him replacing Ryan, when Ryan decided to retire. UVa fans thought Tony wouldn’t be interested, but 
Then Bo finished runner-up to Duke (2015) and announced a farewell tour, saying he’d like Gard to take over, but then left in December of the farewell tour to make sure it’d be Gard. (What’s with these Wisconsin coaches and retiring at really odd times? Coaches from every other state are like “how about I retire at like a normal time?” but Wisconsin guys are like, how about at the weirdest time possible? Did Vince Lombardi retire an odd time or something?)
And then Gard went to two Sweet 16s in a row, so you’re not gonna force a guy out who had done that. And then by the time Greg Gard revealed himself to be Greg Gard, Tony had won a natty, and wasn’t gonna leave (if he ever would’ve anyway – my guess is probably not).