If it is confirmed is part of MH370, could be a news for investigations (good or bad depend on many factors). But, please, don't think this will stop conspiracy theory. Why? This is my answer as a conspiracy theorist.

"But I landed the plane on island X, How much it would take me disassemble a piece from the aircraft, hammer it a little bit to simulate an impact, and drop it in the ocean in a place where will be probably washed ashore?"

That's one of the possible answer. Than it could be: "It isn't damaged enough to be in the water for 1 year, they just soaked it and placed on the shore to be found".

I don't believe in the conspiracy theory, but please, don't think this news will debunk them (actually, it is highly improbable an object traveled so many miles, it has been set up :-) )