what i would be more worried about imo, is 2 things.
a) her passive scaling off base ad aswell as bonus ad instead of just bonus ad, AND a third passive proc on her q might cause her to turn into a worse lane bully than shes now. meaning depending on what else they do with her she might get nerfed pretty soon after the rework. and pushed into a default duo lane role so she doesnt own top lane.
b) her rework pushes her into a adc/support duo lane from the start.
right now quinn is actually one of the few more unique marksmen, as shes one of the only 2 or 3 solo lane marksmen (next to varus and ezreal who can easily be taken into midlane).
her duality as a fighter/marksman makes her already pretty unique. i dont feel like larger changes would accomplish anything in that area.
her current ult also completes the ideal jungle kit. all thats missing would be a decent first clear.
what the rework should accomplish imo is increase her ability to teamfight, with tweaks to her itemization (better synergy with triforce and steraks) and what theyve done with her e should already accomplish. make her a decent jungler (her passive buff and q change will probably help with that). and just slightly less of a bully on top lane.
these changes seem like only half of what has to be done. the other half is to buff dorans shield, so adc dont absolutely destroy melees in lane and just make the matchup a bit more even. right now run quinn vs olaf, darius, garen or any low mobility fighter and they dont even stand a chance during lane phase. on the other hand she kinda falls off midgame if she doesnt snowball.
this rework shouldnt be about drastic changes as theyre trying to accomplish, but more about slight power shifts to midgame, itemization tweaks so she can build better into 1 or 2 fighter items to be more effective on valor, and evening out the matchup between adc and fighters early on.