Without Hal Jordan around, Ollie might've mainly stayed in Star City and not go off to find america, but it's
possible that he wouldn't had spent time with Roy anyway (which would have lead the young man
to taking drugs like he did in the Bronze Age). Harper would still been kicked out into the streets
by Oliver, after he found out about his ward's drug addiction, and would've stayed there for
a while until he got up and walked to either Dinah's home or wandered around until the sidekick
of the Emerald Archer make a stop somewhere.
Or maybe, Ollie or anyone/body could've gotten the kid off the street instead.