Darwin Award
U19 Captain
Given that Root is still keen on playing for a few years more & given England's regular tests they play he'll at least take that to 250 and then some.
Only way Smith can surpass him and keep it if Root retires in the next 18 months or so and Smith keeps playing.
Otherwise,Root is going to hold this record at least for the next 15 years or so because there is absolutely no one else on the horizon.