Romney probably would handle the coronavirus crisis much better than Trump did, based on his experiences with the Big Dig tunnel collapse in Boston.
That said, it's unlikely the effects would carry over to a Vice President Ryan.
Former POTUS Barack Obama (D-IL)/Governor Tammy Baldwin (D-WI) (I'm assuming Baldwin loses the 2012 Senate race, and runs for Governor in either 2014 or 2018 and wins then.) 364 EV 53%
VPOTUS Paul Ryan (R-WI)/Senator Ted Cruz (R-TX) 174 EV 46%
Honestly, it's really only the fact Ryan has the endorsement of the rising in popularity, Romney that keeps this from being even more of a blowout, and Obama's relative mediocre approval ratings also keep him from reaching 400 Electoral votes. About fifteen states are within a five percent gap.