can nidalee still be played mid lane?

Can Gangplank be played midlane?

If you want to do it then go for it.

You're going to have a shitty time against Assassins or lock-down mages like Malzahar. I prefer not.

Short answer: No.

Slightly longer answer: Yes, but it's probably a bad idea.

Long answer: Technically, yes you can. You can play (almost) any champion in any lane and make it work if you're good enough to do so. Yi support can work if you're good enough to do it well.

However, just because it's possible doesn't mean it's worth the effort. You'll do better for less effort on an easier champion. You can hit 50% winrate with Nidalee midlane, but odds are you'd be hitting 70% or higher with any "normal" midlaner then.

It might work as a specific counter, but for it to be strong it'd have to be someone who can't punish you that hard for clearing waves in cougar form (meaning a melee who's weak in early game), and who is highly vulnerable to Q poke. Maybe Gangplank?

Like, if you figure out how to make it work, then go with it. I figured out how to make Morgana mid work well and I still use it to this day. However, it may just not be worth the effort to learn.