http://www.fas.org/man/dod-101/sys/land/oicw-003.jpg&imgrefurl=http://www.fas.org/man/dod-101/sys/land/oicw.htm&h=529&w=800&sz=47&tbnid=gs4wLfqyhTbOZM:&tbnh=95&tbnw=143&prev=/images%3Fq%3Doicw&start=1&sa=X&oi=images&ct=image&cd=1">http://www.dean.usma.edu/cme/images/AAI-oicw.GIF" width=573 NOSAVE>http://hkpro.com/oicwtree.jpg" width=300 border=0>

OICW, as Herald1234 noted, ain't coming down the pipeline any time soon, if ever.  Just imagine going into a building to do CQB with that thing and I think the reason why becomes apparent, even if they get the overall weight issue solved.

 

There is likely to be a replacement for the M16/M4 selected within the next ten years.  XM8 is not, to me, a strong contender -- from what I head about the troop trials, every problem the XM8 solved from the AR-15 pattern was accompanied by a new XM8 unique problem.  Most notably, they melted under sustained fire.

 

If the FN SCAR-L works out in SOF usage, my guess would be it is the next US general service rifle.  Caliber is likely, but not guaranteed, to be 5.56mm.  More interesting is whether it will still be a conventional brass cased round or caseless or CTA.

that ghastly bastard will get scraped, waste of tax payers $$ and materials if you ask me

I don't think the XM8 will ever come about. With Congress trying to get rid of 'waste' in procurement, I would expect for the project to get cancelled. What is wrong with the M-4/M-16, anyway? Accurate, rugged, light, etc. Just keep the M16 and add some red-dot scopes

The XM8 was an attempt to do an end-run around the usual procurement process, with the plan by some idiots of note somewhere in the system being to just adopt the thing without an open solicitation for other designs, etc.  Luckily for us end users, that fell through under threat of law suits and such.  I say "luckily" because my understanding is that the Rangers who did troop trials with the XM8 discovered that it's polymer components melted under heavy firing. 

 

Always nice when a design finds new ways to break, rather than fixing existing problems.  Add to that the fact that the XM8 actually gives up the modularity of the AR design, and you just don't have a winner.  Add in the idea that a fixed barrel (and melting plastic equipped) XM8 with Beta C-Mag was supposed to be the SAW replacement, and you've gone from "not a winner" straight to "disaster" in my opinion.

 

More generally, the XM8 brought next to nothing to the table that the M4/M16 could not already do.  Replacing the one with the other, as you suggest, would have been a monumental waste of $$$$.  If we're going to spend the money on a new rifle (and within the next 10 years or so we will), it will, hopefully, bring a lot more to the table than HK advertising hype and fixing things that aren't really broken.

The XM8 may or may not enter service.

It is a slighly modified H&K G36, with greater modularity, and funky space age furniture.

I'd say the odds are quite lean on it ever happening.  As I understand it, HK sold the XM8 design to some other defense company after the failure of their attempt to push it through military channels.  It's really more a contemporary of the M4 than a later generation of weapon, and so it just doesn't offer much improvement.  The times I've been able to put some rounds through a G36, I found it to be a pretty good weapon but not the earthshattering next big thing a lot of people seem to think it is. 

For a US military replacement to the M16/M4, it will have to go up against the FN SCAR, which, by the time such things are really looked at, will be the SOCOM standard issue weapon.  The USMC is, apparently, interested in SCAR as well, already (but maybe, crossing threads, that's just because all marines are super commandos the day they graduate basic training or whatever, and so they need a commando gun or they might not feel good about themselves).  Assuming SCAR does not have any major hiccups in service, success with SOCOM will probably build a lot of desire among everyone else to have the cool kids' gun.

 

Of course, by the time a replacement is considered, we may be looking at something in caseless or CTA ammunition, etc.