Incentive to be a soldier includes a possible prison term if one is drafted and chooses to evade, so it's not entirely money driven, and death probability is not clear most of the time. It's safe to say that as long as state can provide supplies like food, equipment and munition, there will be enough fighters.
The question then is, again, which state will fail to do that first, the one which can inflate its currency or the one which can't? Historically states which can inflate has proved they can prolong wars just fine.