This is a mod in early stage I just started to work on. Exact mod name yet not decided.
The main feature will be to dismiss vanilla assigned housecarl and the ability to recruit your own...somehow similar with recruiting blades or stewards. I will also aim to give housecarls something useful to do.
The mod will try to be lore friendly, yet the lore for them is not sufficiently established in ES so real world premedieval lore will be the model. This means housecarls are bodyguards, warrior type, they won't do your groceries.

Candidates NPC
Enough candidates will be provided so you can have all the housecarls males or all females.
It will be done via factions mechanism, hopefully using vanilla entries so custom follower mods may provide housecarl candidates.
You'll be able to make additional candidates via console command (addtofaction) with less glitches then the similar method to make marriageable NPC as the whole system will be build considering that possibility.

Fearures
Dismiss and hire housecarls for each hold.
Sandbox AI enhancements for housecarls.
Monthly wage for housecarls. If you fail to visit them in a month a courier will look for you and if all that fails they will leave your service.
Tasks for housecarls via radiant quests. *Accepting suggestions on what they can do
Delegate your bounty missions to your housecarls.

Compatibility considerations
I will try not to touch any NPC directly, not even the vanilla housecarls. All will be done via aliases. So it should be compatible with any cosmetic housecarls enhancements.
All testing will be done with my current multiple followers and other enhancements mod so expect full compatibility.
Won't be compatible with housecarl AI mods as this mod will provide that. Load this after the other mod to gain other features from there like cosmetic changes

Planed releses
There is no ETA on this
Initial release won't require Hearthfire and will work for the four non addon holds with housecarls. It will include wage and maybe a radiant job or two.
After that it will require HF, will have support for all HF holds with housecars and future support will be only on this one.

Reserved

Please let me know if there's other mods providing housecarl hire function cause I could not find any.
Awaiting feedback on the idea and suggestions for housecarl radiant interactions.