Doubt it. Because of the way his passive requires him to walk over dead minion bodies, he has to get uncomfortably close to the enemy top laner (note: they're usually hard-hitting bruisers). Combined with his abysmal base defenses (bcuz he is support, lols!), I can only see Thresh dying and feeding the enemy top laner more than anything.
No, I honestly don't think his shield will keep him alive and healthy enough. The base amount on the shield is lower than even Riven's shield (that's saying a lot) and its cooldown way up to 22 at r1.
His Flay will not help him with the lane either because it's a wide-ranged AOE sweep with a 1.5 second slow. The slow amount is almost negligible in the case of top lane (because they all are either mobile enough or too mobile) and its AOE nature will only damage and push your lane.
His ability to harass with his Death Sentence passive might be nice and all, but just the nature of top lane will kill him. The only possible way I can see this working is if he enables some sickass ganks with his jungler using his lantern tosses, but it would essentially require the jungler to sit on a HUGE babysit duty because you're waiting on Thresh's passive to ramp up a respectable number that would enable him to fight the enemy top laner as well as hope that Thresh as a champion himself can do something for your team when the time comes.