@Garry: I do not think that at the moment, BMPT can replace tanks. But I think at the time when the technological level has reach the sufficient level, the ATGM can be reliable enough to be the main way for dealing with heavy armour instead of tank ammunition and at that time BMPT can be the main player.
A tank has two primary uses... one is to fight enemy tanks for which its high velocity heavy calibre main gun is critical. The other is direct fire support for infantry on an armoured platform with very heavy armour... a sort of mobile bunker with heavy artillery gun fitted.
When the enemy does not have its own heavy armour then the heavy gun on a MBT is used for HE rather than anti armour use so in that case a 100mm rifled low pressure gun can do the job.
Keep in mind these vehicles will be net centric with data coming in from UAVs and satellites and aircraft and a range of ground platforms and will have excellent communications and sensors and also state of the art NERA and ceramic armour as well as the new replacement for Shtora and of course a new APS system that will probably deal with top attack weapons and APFSDS rounds too.
In addition to high mobility they should have good situational awareness and be able to choose when to fight and when to call in air or artillery.
In Iraq Abrams tanks were destroyed by IEDs as small as 50kgs exploding near them... imagine a 40kg 152mm guided artillery shell landing on its turret roof. Or a 130kg 240mm round from a Tulip...
For a number of people, ATGM is one of the most important element of a BMPT, and as you can see, they think this is the key for the future dominating role of BMPT instead of tank cannon + turret traditional MBT. They also see the families of unmanned turret vehicles is one step ahead for fulfilling that model.
Sorry but they are WRONG.
the ATGMs fitted to the BMPT wont be fitted with HEAT warheads... the BMPT is a tank support vehicle... it supports tanks. Tanks are excellent at fighting other tanks... that is their main purpose. The BMPT wont be fighting other tanks it will be fighting the enemy infantry supporting the enemy tanks.
The ATGMs on the BMPT will be for hitting point targets out to 5-6km range... including aircraft and ATGM missile teams.
There is enormous scope for remote unmanned vehicles but there will need to be unmanned MBTs, BMPTs, etc etc. Of course it would be stupid to have unmanned IFVs and unmanned APCs for obvious reasons, which is why you need unmanned BMPTs as they will deal with the enemy infantry and light armour, while the MBTs will deal with enemy heavy armour.
The BMPT weapon combination of ATGM/Shmell + 30mm autocannon (HE and AP ammo) + grenade launcher, I think, provide superior capability in dealing with both hard and soft targets, and very close range AA tasks (anti helicopter, etc). Given if the ATGM is reliable enough.
The BMPT supports tanks with 125mm smoothbore main guns... it has not capability against heavy armour.. the ATGMs will all have HE warheads.
I suspect the BMPT will change to Kornet-M missiles to extend its anti aircraft capability to 10km... a capability it was designed for and is being attached to Pantsir units as a cheap short range missile against UAVs etc.
Back to the lightweight chassis, I still prefer ATGM and small caliber auto-gun rather than a bulky cannon with big turret.
The 100mm gun of the BMP-3M is a powerful and fairly accurate weapon and the new missiles being developed for it appear to be the size of the standard HE rounds so instead of being limited to 8 missiles and 40 odd HE rounds ready to fire it should have the potential for perhaps 48 rounds ready to fire with up to 48 guided missiles or 48 cheap HE frag rounds.
Experience with the BMP-1 with its 73mm gun and the BMP-2 and its 30mm cannon has shown the Russians that it is useful to have light auto cannons and also heavier guns firing heavier more powerful HE rounds too. For a lot of targets the 30mm is ideal, but for other targets it lacks weight and impact while its rate of fire is of no use. A much heavier round makes sense, but lighter higher velocity rounds in an automatic weapon are also useful.
In many ways the BMP-3M was the BMPT in that it could support its infantry unit against enemy infantry forces but has some self defence capability against tanks it was not designed to fight tanks.
The BMPT on the other hand has no capability against enemy heavy armour... but it also doesn't need it because it is designed to operate with tanks which can deal with enemy tanks.
To put it in perspective I remember a photo in a British military magazine from the 1980s that showed a Bradley firing a TOW missile stating that it could kill a Soviet tank out to 3.75km. At the time they didn't realise that was not 100 percent likely, but they did comment that the enemy could be a T-80 firing back APFSDS rounds at 1.8km/s and that while launching the TOW and guiding it the Bradley would have to remain stationary while the T-80 could be moving and fire 2-3 rounds in the time it takes the TOW to reach it.