And don't call it "Son of Rambo", please.
Or Rambo's First Bloodkin
If it isn't about his son, the only other thing I can think of is the show be some kind of memoir and Sly is the narrator. Recasting is perfectly fine, (Milo?) but you can't really pull a Nimoy with time travel.
Otherwise, it they try to skirt the issue like they did with Jason Bourne or use "Rambo" as some kind of title would probably fail.
All in all, been a big Rambo fan (Even Rambo III
.) since I was a kid. I'll probably tune in.