Not sure if i want an ms-boost for the dew no-escape carrys, but they could use the kog-treadment of atleast having superior dmg/rang or tankiness.
Tris is about the highest dps champ with also highest range and great selfpeal, lucian got the best short trades and strng poke in lane aswell as hyper mobillity and high dps.
Kog works without selfpeal cause he got high range, insane damage and the highest base-hp lvl 18 amongst carrys.
Jinx also works cause she has massive dps and high range.
So, what is left on no-mobile adcs?
Varus got great poke, wich therefor costs some mana and windup with even less mobillity, and some nice cc, but the poke isn't much better than cait/Jinx or Kog post 6, and the cc dosn't make up for the lack of mobillity and range, and his dps isn't higher than that of mobile champs.
I think he deserves 25 more AA range, and maybe a bit more base as.
Ashe has great utillity and some good poke/range, but she lacks dps and survivabillity. and the range isn't that great compared to jinx/cait/tris/kog.
I think some on-hit damage on her Q would already help, and a small increase on the W ratio to help out her low damage.
Or simply a passive.....
Missfortune needs a cleare direction, should she be a hybrid caster ot ad-carry.
she would have the potential of huge aoe-damage, or hybrid dps, but she underpwerforms on both roles
makeing her W physical damage would help alot on delivering damage mid/late with her
giving her W an ap-scaling would make ap-mf a dangerouse hybrid carry
giving her E an ad-scaling would help her to deal enough hybrid-aoe in the mid/late to stay relevant without %pen
TL/DR: I don't think imobile carrys need more mobillity, but rather better defined strengths that allow them to be viable despite the lack of mobillity(like kog/jinx) while mobile carrys need some better deffined weaknesses(unlike lucian/tris)