(First time poster, but I don't shy away from receiving criticism :) )
Let's assume that there are two great powers that are vying for dominance over the planet, but neither of them has discovered nuclear fission/fusion (apart from that, they progressed along similar lines to our civilization.)
One of these powers is a theocratic republic, relatively highly motivated in their efforts to convert other states to their religion. They're also OK with using their military might to force it on others as well. They have a capitalist economic system, where every corporation is obligated to invest a percentage of their profits in local infrastructure.
The other power block is made up of a larger and numerous smaller monarchies, mostly constitutional ones, that are not interested in direct territorial expansion, however they don't oppose the idea of creating a buffer zone.
The populations in the former block are pretty much brainwashed into believing that spreading their faith is a cause that's worth dying for. In the monarchies, there is about a 50/50 split between militarists and pacifists.
Infrastructure (roads, railroads) are at about contemporary European levels in the urbanized/strategic areas, however near the border they are quite neglected. There is also the possibility of transporting manpower/equipment by aircraft, I guess.
There is a long land border between the entities, that is mostly desert. The natural resources are roughly evenly split, with the 'border desert' being richest area in oil and natural gas, however previously neither states invested in the area, previously, given it's location.
The various secondary powers do not share a land border, they are located on the coasts and as such instead of supporting a strong manufacturing industry, they rely on trade to sustain themselves. As a result of this their desire for direct confrontation is lower than that of the two 'superpowers'.
Would this mean that unlike in the case of the Cold War, hostilities still escalate beyond the scope of local proxy wars?