It's very possible at some point FG was planned as Archer, but once the story started to take shape, it must have changed immediately.
If they wanted it to be Archer, then that's what they wanted. Nothing about what I understand about Future Guy and his influence over the Suliban seems to make any sense at all with it being Archer. On the whole, he's a very decent human being through the Enterprise's missions. Can you see him being responsible for the Suliban? Changing their species and helping to distribute stealth technology? How does he justify that?
I think Manny Coto would've had different ideas, based on a comment he made at a convention once
. But Future Guy is a Berman and Braga creation and they'd have the final say.