It would be nice. Although they could’ve tied Robin into the overall story better by having him be the one that taught Snow to shoot. Having Robin be an old friend of Snow would’ve then given him a relationship outside of OQ, would explain why he was so into Regina upon meeting her (because if Snow is okay with her after everything then there’s no reason why he shouldn’t be), it would have made the whole Reina killed Marian originally a bit more tragic, and it would’ve made OQ make more sense. Alas we are where we are.
In my estimation, fans come up with better ideas than the writers 90% of the time. It seems like such an obvious tie in that I’m surprised the writers never went that route. Why not have Robin have connections to more people in the town than just Regina and now Zelena? The writers really just don’t know how to come up with ideas that create good characterization. Now it seems they really will write him out entirely. Maybe they always planned to kill him off (at least since late season 4 or early season 5), but they could’ve avoided this conundrum by avoiding the icky rape situation and by making Robin interact with more people in situations that are actually pertinent to the story being told. Why not make Arthur the treacherous king that Robin Hood stole from to order to give to the poor? Robin could’ve had an entire backstory in Camelot with Arthur, and maybe Mulan could’ve come back for an episode and been shown as part of Robin’s band of thieves.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy