The 100/30 evolved from the BMP-1 and BMP-2 and their 73/30 gun combination between the two vehicles that were found to be complimentary rather than one replacing the other as expected.
Of course the 100mm rifled gun is a huge step forward in performance over the 73mm, but the 30mm hasn't evolved as quickly as the enemy armour it was supposed to deal with has.
The obvious replacement for the 30mm therefore is the new 57mm gun, but its potential for HE power means it can also practically replace the 100mm too.
Obviously a 100mm shell will carry more HE than any 57mm shell, so there will be some loss in performance in terms of HE power but as each unit will also be supported by tanks with 125mm guns able to fire HE rounds and also artillery able to offer 120mm and 152mm calibre guns and also rockets of various calibres I don't think that will be a huge problem.
In terms of the transition from 30mm to 57mm there will be a large step up in effective range and armour penetration performance and effect on target that will reduce the amount of work the organic tank units will have to perform... heavy enemy IFVs will no longer need to be engaged with 100mm missiles or 125mm guns...
This vehicle could be a new upgraded export model, or a test example.
Once the 57mm calibre is fully ready for service I think the 100/30 combination will become redundant.
In fact I think a good solution would be to replace the 100mm with a 120mm gun/mortar system... eliminating a calibre from the inventory and stores without reducing performance and capability... the 120mm gun/mortar can fire rounds to almost double the range and has more powerful HE rounds and also can use 120mm and 122mm guided rounds.
I would still use the 30mm for a while anyway... but even in air defence I think guided 57mm shells have more promise than just firing thousands of 30mm shells and hoping for a hit.