An equilibrium will develop. If you want to fight an interplanetary war, your soldiers have to travel through an environment that will do to them what a wood-c

An equilibrium will develop. If you want to fight an interplanetary war, your soldiers have to travel through an environment that will do to them what a wood-chipper does to decomposing animal viscera. It's unavoidable. If it turns out we can't make survivable ships, space is the ideal interdiction environment. Kill 'em out there before they can get down here. Some areas of space (e.g. certain planetary orbits) are naturally important because they allow you to exert influence on combat elsewhere (e.g. by dropping dense objects on the enemy). So as ships become more survivable, it becomes more feasible to try and garrison strategic positions, and space battles will 'just happen' as opposing garrisons come into contact.