Do note, I am talking with my limited understanding of the subject. Its not like I have studied these topics formally, so viewer discretion advised. Members like
@Bhadra @rvats and
@mist_consecutive are more informed on these things.
That's a very good effort to elucidate the role of infantry in various formats.
Just a couple of points:
(1) There are two broad concepts - one is mechanized infantry and the other is motorized infantry.
(2) As you've already mentioned, mechanized infantry is one which is equipped with Infantry or Armored Fighting Vehicle (Tracked) or IFV/AFV (Wheeled). Our FICV is IFV (Tracked) replacement for BMP-2 while Kestrel is a candidate for IFV (Wheeled).
(3) Motorized infantry is equipped with vehicles which provide organic transport under limited protection. The watered down Kestrel (Infantry Protected Mobility Vehicle), Kalyani M4 and TATA MPV are all examples of platforms for use by Motorized infantry.
(4) Motorized Infantry is a term which was popularized by the Soviet Red Army. They had mechanized infantry battalions and brigades and divisions equipped with BMP-1 and BMP-2 and Motorized Infantry Battalions/Brigades/Divisions equipped with BTR-60 series of vehicles.
(5) General Sundarji's Army Plan 2000 called for 4 x Armored Divisions, 8 x Mechanized Divisions and 7 x RAPID plus mountain divisions.
(6) RAPID consists of 1 x Armored Brigade (2 x Tank Regiments + 2 x Armored Regiments) and 2 or 3 infantry brigades.
(7) While the Armored Brigade has full mobility, the Infantry brigades are hamstrung in terms of organic x-country mobility to keep pace with the armored brigade.
(8) Indian Army has been using 4x4 TATRA high mobility vehicles for these infantry brigades to provide them x-country mobility. But at the end of the day, these are soft-skinned vehicles with no protection.
(9) So how do you balance out mobility aspect of a RAPID? Convert the infantry brigades into motorized brigades. Where battalions are equipped with organic platforms like IPMV, M4 of MPV (depending on terrain, task and challenges).
(10) Compared to creating a full fledged mechanized infantry divisions, this is a low cost option for provide mobility to your troops.
(11) Plus, the platforms can be equipped with RCWS, ability to fire an ATGM from under the vehicle, mobile mortar platforms, loitering ammunition, drones and a mix of light tanks or AFV (Wheeled). Your standard infantry battalion suddenly transforms into a powerful unit with mobility, ISR assets and stand-off capability.
*Each Stryker Battalion was supposed to get 9 x Stryker Mounted Gun System (MGS) which was basically a Stryker APC with 105mm gun (a light tank by all means).
(12) A hypothetical IBG for eastern Ladakh could be 1 x Mechanized Infantry Regiment + 2 x Motorized Infantry Regiments + Other support units.
(13) One more data point for you - Procurement of Wheeled IFVs is being done by Director General Mechanized Forces (DGMF) while IPMV, K4 and MPV is being done by DG Infantry. This tells you the planned use and employment of these formations.