You have the Redskins drafting Mayfield in the 1st. In this scenario I am assuming the Redskins drafting a 1st round QB means they did not retain Kirk Cousins. So where does Cousins land?
Considering you have nine teams (including the Redskins) taking a 1st round QB and two more in the second I'll assume he doesn't land with any of those eleven.
Or the bakers doezen with established starters or recent 1st rounders: Seattle, LA Rams, Tampa, Atlanta, Carolina, Chicago, Detroit, Dallas, Philly, Oakland, KC, Houston, Tennessee
Seven more are possible but unlikely
San Fran? Doubt they would trade a second for Jimmy G then sign Cousins
New Orleans? Does Brees retire?
Green Bay? Is Rodgers injury a career ender?
Minnesota? Already has three viable starting QBs on the roster (2 coming off injury)
Indy? Will they cut ties with Luck
Cincy? Will they cut ties with the Red Rifle
Baltimore? Will they cut ties with Average Joe
Which leaves two landing spots
Denver
Miami