Is This Realistic

No, I do not think it is realistic

Not realistic trades, not realistic contracts

Devils dont move Mercer for 8 years of Fiala let alone 2 of Nylander and the injury prone Muzzin

Devils trade isn't really close at all.
There's no point for them to trade a long-term core piece for two years of Nylander, especially when they probably won't be competing for the cup in that timeframe.
Wouldn't rule out Mercer being as good or outright better than Nylaner in two years time either.

Honestly don't see the point in Leafs trading Nylander either, he's a fantastic player on a good aav.
These last two years of Nylander pretty much covers the length of this current window of contention for the Leafs as well.

I actually think this is fairly realistic. Couple of notes:
- I think dumping Mrazek costs more (maybe add a 2nd)
- Trochek probably costs more as a UFA, I'm thinking closer to 6.5 mil

Besides that I think it's alright and Trochek seems like he'd be a great fit for this team if they move Nylander.

Holl has value, don’t need to give up that much for Mrazek either