With the loss of powers, how about try them as a +4 LA race?
Here's a stab at statting them out in a 10 level class. I gave them more natural armor at the start, since without any magical powers they will need some kind of combat ability. I also gave them their full intelligence boost up front, as otherwise their skill points are off. (An increase in the intelligence bonus doesn't retroactively affect skills). Damage reduction is gradual.
I gave them tongues as a lesser succubus ability. It can be cast as a free action even on someone else's turn, so it should work out the same as the standard succubus ability. Telepathy is gradual; first they can only communicate with demons, then they can only communicate in abyssal, and finally they can communicate with anything with a language. By habit and custom they will use tongues to speak with mortals.
Saves, skills and BAB can all be computed from their hit dice, so I'll leave that out. And refer to the 3.5 MM for explanations and clarifications.
The Succubus:
[Insert Flavor text here]
Outsider traits: good BAB, Good saves, skill points/level = 8+int bonus (x4 at 1st level), darkvision 60 ft., cannot be raised, proficient with all simple and martial weapons. Outsiders breathe, but do not need to eat or sleep (although they can if they wish).
Starting Ability Modifiers: +6 Int, +8 Cha
Class skills: bluff, concentration, diplomacy, disguise, escape artist, hide, intimidate, knowledge (any), listen, move silently, search, spot, survival, use rope
Skill bonuses: +8 racial bonus on listen and spot checks. +10 circumstance bonus to disguise checks when using alternate form ability.
Code:
1st level 1d8 2 claws 1d3, alternate form (1), +5 natural armor, SR,
subtypes (chaotic, evil)
2nd level 2d8 +2 Wis, lesser succubus powers 1/day, resistances 5,
telepathy (100 ft. demons only)
3rd level 3d8 +2 Cha, alternate form (3), +6 natural armor
4th level 3d8 +2 Dex, lesser succubus powers 3/day, telepathy
(abyssal only)
5th level 4d8 +2 Cha, alternate form (any humanoid), energy
drain 1/day, fly 50 ft. (average), +7 natural armor,
resistances 10
6th level 4d8 +2 Con, DR 5/cold iron or good or magic, lesser succubus
powers at will, succubus powers 1/day
7th level 5d8 +2 Cha, energy drain 3/day, +8 natural armor
8th level 5d8 +2 Wis, DR 5/cold iron or good, electricty immunity,
succubus powers 3/day, telepathy (unrestricted)
9th level 6d8 +2 Cha, energy drain at will, +9 natural armor
10th level 6d8 +2 Str, DR 10/cold iron or good, succubus powers
at will, summon tanar’ri (vrock 30% chance)
Spell Restance: SR = succubus class level + 8
resistances: acid, cold, electricity and fire
lesser succubus powers: darkness, detect good, detect thoughts, suggestion, tongues (immediate action)
succubus powers: charm monster, ethereal jaunt (personal plus 50 lbs of equipment), greater teleport
(save DC = 10 + 1/2 hit dice + cha modifier)