I'll echo
@Infanteer's and
@TangoTwoBravo's comments above and will pile on a bit.
My most active time was in the 70's and into the early 80s. By that time we were down to 3 companies per battalion. While they all had mortars, anti-armour and pioneers, they were never considered a mini-battle group albeit their configuration was sufficient for many of the peacekeeping efforts at the time such as Cyprus. However, almost all of our training centred on Europe. The Combat Team Commander's Course was the foundation of how to fight there. Combat teams and battle groups were always built around armoured troops and squadrons, artillery batteries and engineer troops were the de rigour model we used throughout. (Engineer regiments hadn't been invented yet - each Combat Group had one engineer squadron)
Towards the end of the century we had deployed numerous rotos to the former Yugoslavia which had gone in various configurations; some with arty, some without - no tanks though. Those deployments were a huge drain on the army for personnel and a lower level of intensity combat training (we stopped doing divisional exercises and for the most part gave up brigade ones). That and the financial cuts of the 90s drove the transformation model that produced the Advancing with Purpose transformation agenda as modified by the subsequent Afghanistan experiences.
Note as well the experiments in the latter 00s towards an "optimized battle group" which was an attempt to design standing battle groups which required less ad hoc configuring. Those never panned out. I'm firmly in the camp of those who feel that the basic division of the army into infantry, armour, artillery and engineers as the backbone with additional attached services is the proper model developed in over a century of conflict. Yes there is a need to update doctrine from time to time as new weapon systems are developed, but there is no need to fundamentally radically change the components. Each of the existing components can quite easily incorporate and adapt to revisions in doctrine.
I don't think its the drive train that matters in
@KevinB's viewpoint. His view, and mine. is that a proper infantry/armour combined arms team requires the infantry component to fight differently than a light or mech infantry component that does not operate with tanks. I'm not sure as to whether you agree or disagree with that proposition. My opinion comes with having been a FOO working with mech (M113 no tanks) inf in Pet and on the CTCC (M113 and Centurion) and German Panzergrenadiers in Shilo (Leos and Marders). In each case different small unit level tactics were employed that directly impacted on how the sections and platoons worked notwithstanding that they all had tracks.
Our view is solely that the tracks on an IFV facilitates the ability of the infantry to keep up to the pace of the tanks which might not be as easy with a wheeled IFV regardless of how well it is armed and armoured. The tracks ought not to affect the tactics the infantry uses, but merely makes it more possible to do them effectively.
In my mind I see an basic infantry course that teaches a recruit everything that applies to all infantrymen and then have them have a small package that is divided into light, mech and combined arms. Whether done at a school, regional battle school or at the unit is immaterial to me. What is the issue is whether it is all taught on the basic course - and thus lengthen the course - or in finite specific packages that can also be taught to people transferring from one type of unit to the other, is the real issue.