Probably an overdone trope, but what if he did? The period 1841-1849 (or even 41-45) was an important period in American history, including the annexation of Texas, settlement of the Canadian border and the Oregon territory, and the war with Mexico. These events and the time period also lead up to the debate over slavery. What would have happened if he survived?
I think one effect is that clear Presidential succession resolution is delayed, or altogether different.