Probably already under examination. All the services keep a close eye on other development programs, and there are internal discussions on what use any and all equipment might have. Traditionally the Marines have made use of anything that fell their way. Back in 1993 I met a Major who was bragging about having reequipped the Marines with a cast off US Army MMG (in unused condition) for scrap prices.

If FCS gets fielded I would imagine the USMC will end up using some elements of the family of vehicles. There was talk of the USMC building their own MBT design, but I just don't see Congress buying into the economics of that -- they can rightly justify Marine peculiar systems they need like AAVs or Harriers or even the V-22, but it gets trickier with relatively generic items, especially the big ticket ones where the economics of having two similar systems in the inventory are debatable.