Regardless Vitalik die or not, Eth will run as normal but the price will be doping a bit when Vitalik really die but soon after that the price will goes up.
Yes, Ethereum will not be affected in anyway. Ethereum is a project and Vitalik is not indispensable as anything can happen. It is more like saying when Steve Jobs dies, did Apple crumble? No, it did not and we still keep seeing apple in the same light as we have been seeing it. One thing is that the market will move on, Ethereum will move on as there are so many developers on board and we will only have a name to remember for Vitalik for coming up with some smart contract platform in the long run. At least, he is a unique figure in this space whether we like it or not.if Vitalik dies, many things could happen either good or bad. Perhaps, Ethereum may fall if Vitalik dies, because he's been leading the project every step of the way. By not having a leader, the Ethereum project will disorientate itself into oblivion, IMO. Nonetheless, what are your thoughts about this? 
I am able to understand your concern over being a centralized project. I just wonder about 1000s of other coins which are all being taken care of its one developer or group of developers but if something will happen to them, how it will move to next step. I had never thought in this perspective but now onward need to analyze on this matter more seriously.