Let's start a discussion on Nautilus's Future in League
Nautilus initially was a tanky, cc heavy jungler that had very clear windows of opportunity where he could succeed as well as downtime where you could really punish him. Most of his damage and defense was packed into his W where good players could either bait it out or have their frontline stall him and then punish him when it went down. If he missed a Q, he was stuck in the same spot and you could pepper him with ranged abilities while he had no escapes or engages. He was considered either a sleeper or a below average jungler for years despite having good utility (I think Trick2g used to call him uselessness).
Along the way, Riot decided to shift his power budget from his W into his E so he could deal with the AOE heavy camps more easily. The intended goal was to spam e for better clearing but in exchange he lost all of the damage that his W provided. This led to unhealthy gameplay (mostly in top lane) where Nautilus would become a difficult to kill pushing machine and made an experience that was not very much fun to play against. He also appeared in LCS fairly common which was unusual for him and led to probably a little more heavy handed nerfing than if he was doing well in Bronze, for example. He started to appear more in bot lane and really started to disappear in the jungle (even with Cinderhulk's heyday he was secondary to Gragas, Sejuani, Amumu, and Sion in popularity.)
Recently Riot attempted to fix this by adding additional mana costs to his E where spamming it is no longer an option (in hopes to get him out of top lane I suppose.) He was roughly a 50 percent win rate top laner at the time so I assume they wanted him out of there for the unhealthy gameplay. This leaves him with some problems because he no longer can perform his jungle clears because he can't spam his e to damage them. Remember, the initial intent for his jungling changed were to shift power and a low cooldown into his E for clearing, which these new mana costs have prohibited him from doing. I would like to report his jungling win rates but the play rates are too low to appear on sites.
So what should happen to Nautilus? I think 2 things. First, develop a clear identity as to where he should be playing. At this point, it is either in a support role or jungle. If Riot wants to bring him back into popularity with the jungle, they should add monster damage to his E so that lane Nautilus can't benefit very much from this added power. If they want to bring him to support, they should add power to his shield because he's not going to be able to acquire enough gold there to add the health needed for his transition to late game (his shield scales on health), especially with tank items recently being nerfed with health across the board. Anyway these are my 2 cents. I like Nautilus and want to see him in a good and fair spot.