It would seem the player’s character could lay claim to being the reincarnation of Tiber Septim (since you do appear to repeat a lot of what he did: the greybeards take you under their wings, your master the thu’um – a true son of Skyrim, and are a successful war cheiftan), or at least make claim on the (vacant) throne as being one of the most powerful warlords there is?
By the end of these two quest lines your character is dragonborn (if it still existed, wouldn’t your character be able to wear the Amulet of Kings?), has mastered the Thu'um, is supported by the blades, and have rebuilt the blades around people loyal to you (the veterans appear to give orders and act independently, but the recruits follow you). Your character already has their own private army of huscarls (my understanding is that historically huscarls provided the core army and militia bolstered them), and has more than likely raised the funds to be able to field their own army anyway. If you sided with the legion, you are a legate and wouldn’t you have access to imperial troops? Likewise with the stormcloaks. By the end of the of civil war and main quest you have more than likely helped more than the odd person and became thane in numerous locations, thus have gained vast political and popular support from all over Skyrim.
So, shall we march on the capital now?