The two options seem quite similar.

I guess I just wanted to know what will happen after the One Piece's found, since the Great Pirate era was started for the race to find the One Piece.

It's like the Space Race era between the Soviet Union and USA of 20th century in real life comparison.

I think that the Great War will begin as soon as the One Piece is found, just like the prophecy Whitebeard gave!

The Era will keep going, but One Piece does seem like it will end with an epilogue (telling what each Straw Hat is up to)

I wanted to say it wouldn't end cause usually pirates do their own thing and they could easily pop out of no where, but Luffy's era will come to an end once he becomes King just like Roger. Any person can become the King or Queen, but your era has to eventually come to an end no matter how powerful or good hearted you are.