Because the verb can is defective in English, it's hard to imagine what poder means outside if present or past (where poder generally translates to can's old past tense, could).
Sometimes for other forms like the perfects (he podido, etc) or potentials (podré, podría), it can be easier to switch to English's periphrastic equivalent, to be able. When used impersonally and in the present/past it would translate better with the pair of also-defective verbs may/might, it tends to make more sense as to be possible or as the adverb possibly with the other verb placed in the appropriate English tense.
In this light, we can see that this sentence says that the personal appearance will possibly be required. In English, we would simply render this, though, as a personal appearance may(at such future time) be required.
The consulate, of course, based on that law is free to require it, but may if it chooses, opt not to require it.