FN gave us the PS90 and FS2000. They are not going to give us the SCAR, that's a SOCOM toy.
What?
Anyway, I too am hoping for a semiauto SCAR Heavy. While the interchangable barrels might not be especially useful to an individual infantryman (who's not going pack around with an extra barrel in his ruck anyway), it'd be immensely useful for us civilan shooters who want to make the most out of a given rifle platform.
Personally, I'm hoping for a 16-18" mid-weight "standard" barrel, along with maybe a 20-22" heavy barrel. Of course, now that I live in a state where such things can be done, I'd be immensely tempted to put on one of those 12" CQB barrels and pay the SBR tax.
Downside? Well, it won't take the same magazines as my FAL, so I'll have to stock up all over again.
Upsides? The SCAR has a lot going for it. Modular design, long optics rail, other rails without going overboard.
I don't know that I'm thrilled with the stock. I understand the military desire for adjustable LOP stocks, but for my personally, a 13" LOP fixed stock would be just as well.
And for some reason, they insisted on putting a stupid M16A2 grip on their with that annoying little tab thing that goes between your fingers. Easy enough to swap that out, though.
Normally, I don't prefer rifles with the sight line so far above the receiver, but...it's a necessity these days. If you don't do that, but then flat-top it for mounting optics, your stock comb is then too low for cheek weld.
At any rate, I'd put an Aimpoint or something on there and the iron sights would be only as backup.
And I really really hope they make it in some other color than baby poop.
The BIG downside to waiting for a SCAR is that the military is interested. A SOCOM order won't entail hundreds of thousands of units, but I've heard that the USMC is interested in the design, too. If FN gets a major military contract for some variant of the SCAR, then the civvie version will likely go on the back burner. FN is really interested in the civilian market, unlike, say, HK, but big DOD contracts are the cash cow.