Yes, there will be a US-spec GT3RS for the road. We don't know what it will be though. Maybe:

No sunroof
2-piece reclining carbon race seats
Lighter weight (plastic rear window and more composite body panels
No TV-set (Nav) or center console
Widebody (like C4/S)
Special colors (like old 2.7RS) and graphics
Larger rear spoiler and revised front airdam
$20k more money