Don't forgot AMX-10. According to Inventory data that I gather so far, it could be the most numerous armoured vehicle. The number of Marine inventory :
AMX-10 : 50 -80
PT-76 : 50 -70
BTR-50 : 50-60
BTR-3F: 54 (with the latest procurement),
BMP-2/BVP-2 : 30-40
BTR-80 : 10-15
LVT-7 : 10
BTR-4 : 5
PTS-M : 5-10
The above numbers I gather from various sources, so if other members got more precise number please fell free to correct it.
From those number, the inventory that officialy going to be put out are PT-76 and BTR-50. Seems BMP-3F going to replace PT-76, but for me what is not final yet is what going to be the final replacement for BTR-50.
If looking from old printed media in the 80's and 90's, it was mentioned that originally there were more than 100 PT-76 and around 150-200 BTR-50 procured by Indonesia for the Marines in the 60's from USSR. With current inventory of BTR-50 only left to 50-60, indicated along the time, AMX-10 and BMP/VP-2 already replacing some BTR-50.
The lattest oficial statement indicating that BTR-4 will be procured to replaced either PT-76 or BTR-50 (depends on articles). However with Ukroboron so far confirming only 5 order, for me indicating no firm program yet for BTR-4.
What madokafc mentioned of the Marines not really comfortable with BTR-80 access arrangement, already circulated for some time on local forum. For me, by only procured that small number of BTR-80, show that the Marines only evaluating BTR-80. But then again those BTR-80 already being send to International assignment under UN flag by Indonesian contingent.
It could be the Marines find some strong factor of BTR-80 but did not like the access arrangement, which come to BTR-4 that share several BTR-80 qualities but with more preferable (for the Marines) access arrangement. They perhaps need amphibious wheeled IFV, which perhaps explain why not all BTR-3F fleet for replacing BTR-50.
LVT-7 is another factor in here. It's popular and preferable for the Marines (which shown on the frequency of usage in the operational and exercise assignment). According to official statement in 2012, there should be 35 LVT-7 ex ROK Marines will be given to Indonesian Marines. So far only 10, which other 25 officialy still waiting US agreement for transferring to Indonesia. However I more suspected it is tied up to further deal with Samsung Techwin on more LVT-7 procurement. Thus LVT-7 as I mentioned before can be turn out to be more numerous than other vehicle save BMP-3F especially if Indonesian mindef or Pindad can get agreeable arrangement with Samsung Techwin.
Then for AMX-10, it's officialy will be upgraded, but no secret that the Marines did not fondly accepting AMX-10 to begin with in the 90's. It's still relative young age for Indonesian Marines standard, however I got suspicion that it will be replaced soon, if they can get enough budget for something else.
Overall, the Marines seems have plan to standardize their vehicle to 3-4 types, but which one will be, that's the questions.