I wouldn't say kill it, plenty of people still own xbox's and plenty of studios still make cross platform games. what i would is simply stack up some great first party games and get them all in development now so they can be released in time for the next console. Come out the gates swinging next time.
I know plenty of xbox owned ips i would love to play. Do a Jade Empire sequel. KOTOR remake, a new Fable, bring back Sleeping Dogs as your own exclusive GTA series since nobody else is doing anything with it. it would be easy to make a ton of exclusive game that people would love.
Don't throw the bag at studios that who's creative team revolve like doors and fall off just as quickly as they rise (bioware) throw the bag at intellectual properties, game series people love. and continue those. Maybe bring back that people that worked on those games, creative directors and such instead of the studio they no longer work for.