We modernize the infantry equipment instead - that's akin to the introduction of Grey and Brownish uniforms post-1900 at best.
Well let's talk about that though. What if, through modernization and weight savings, an OICW-type weapon with an integrated 20 - 25mm airbust HE munition COULDbe developed and deployed? Assuming a trajectory that supports 500 - 700m engagements with near-pinpoint air burst accuracy, that could be a potential fight-breaker in a lot of situations where an enemy may be behind hasty cover, or light concealment.

How would infantry tactics change if that capability were to come into use, and troops carried a combat load of 60 - 120 rds of 5.56mm, and 24 rds (4 magazines of 6 each) HE or flechette rounds?

I've been a naysayer of the concept for a long time, like many others, because developments so far are just too big.

Perhaps we do not need as precise an effect as a laser range finder and adjacent air burst results, but rather effects like the PAW-20 (where terrain permits):

http://www.youtube.com/watch?v=eu87AxzBf3Y