When the US Army requested funds to up gun the M1126 Stryker Infantry Carrier Vehicle, they asked for more money than really should have been needed if it was a straightforward bolt on upgrade.
But now Lithuania has put out a feeler to purchase 84 of the 30mm ICV vehicles with an M2 flex mount machine gun (instead of an FN MAG or M240B). http://www.dsca.mil/major-arms-sales/lithuania-m-1126-stryker-infantry-carrier-vehicles-icv-30mm-cannon-and-m2-machine
So what does this mean? I think it means that between the 81 planned for the 2nd Cavalry Regiment and 84 for Lithuania, the 165 upgunned Strykers will turn into more than 500 as the US Army has several other SBCTs that could benefit from the addition of a 30mm cannon variant to their formations.
What is very curious is that Lithuania has a whole choice of fighting vehicles to choose from, tracked CV90s, or Polish ROSOMAK, and there are plenty of BTRs on the used market as well. But, given Lithuania’s position, the Stryker holds more dismounts than the other options, and is lighter than the ROSOMAK but heavier than a BTR-80 (although both of those are amphibious from the get go, and while GD has an Amphib Stryker option, Lithuania didn’t specify that capability).
So why Lithuania would choose the Stryker over other options? I can only speculate, but tactically it makes a decent amount of sense for a country that plans to be over run by the Russian Horde and needs to execute a mobile defense as long as possible. The extra dismounts means kicking out more Javelin teams, and it means parts compatibility with the United States Army supply system in the event of a real shooting war. It also means crew compatibility to some extent.
It is an interesting development to say the least.