No., as soon as the elements of harmony break and "die". The entire world will go for equstria, the giffrins, changlings, discord will all rebel against Equstrias rule, and equstria has no defence, well unless the girl scout gaurd can pull there act togehter. Equstria would be gone in a week.
To sumerise,
Equstria has a defence that will last a finaite time, when it runs out, they are screwed.
That is why equstria is niot the most powerfull nation
The offical map for equestria shows what it looks like it doesnt look like the america at all, hmm i think most of the writers are american so the names were made by them,