Hensley is the sleeper candidate to bat leadoff, and while I wouldn't count on it, I also wouldn't put it past Dusty Baker. Last year Baker showed a propensity to bat subs in the same place in the order as the regular they were replacing, regardless of qualifications.
For instance, Niko Goodrum spent more games batting leadoff during his short stint in Houston than he did games batting 8th and 9th in the order combined. Mauricio Dubon was one of the worst hitters in baseball, and led off 17 times, batted second seven times and batted third eight times.
If Dusty continues this trend, he may just leave everybody else in the lineup where he feels they are most comfortable, and decide to place Altuve's replacement atop the order. Enter David Hensley.
Though he doesn't have the home run power the other three candidates possess, Hensley may not actually be a terrible idea atop the order. He fits more of the old school than new school model of leadoff hitter, as Hensley is one to carry a high average and get on base often.
In a small sample size last season, Hensley hit .345 with a 1.027 OPS. He reached base in 44% of his plate appearances. While a .441 OBP may look unsustainable for Hensley, he did reach base at a 42% clip in AAA. He knows how to work a quality at-bat, as evidenced by his performance in the postseason. Hensley is hitting .286 this spring with a .412 OBP and two home runs.
This is the least likely candidate, but don't rule David Hensley out from at least making a cameo atop the order in the couple of months Altuve is set to miss.