Check this out!
It seems that Goto Maki is not only out of H!P, but the entire showbiz.
As already discussed on the UMAI, until there is an OFFICIAL announcement, it is rumors. Even hello-online (your link) says so, when they say
According to a japanese community, Goto Maki not only quited Hello! Project, but the entire showbiz.. Now you see, that part "According to a japanese community" is what makes this "news" tricky, because:
1 - It does not come from official sources (either Maki or UFA)
2 - H!O doesn't even say who or what this anonymous "japanese community" is. For all we know, it could be 2ch (and you know how reliable 2ch info is).
Want more proof that we most probably are in the presence of gossip? The H!O article also says
It was reported that Takahashi Ai cried aloud in front of the staff in Korea when she learned about Goto Maki's graduation and she immediately took a flight back to Japan in order to attend her final concert.
But the problem here is, Aichan, Gaki-san and Koharu all flew back from Korea TOGETHER on the 28th, after doing a final radio interview, and I know someone who was at the airport for their departure. Given that they were in Korea officially for the first time, and that they had a very busy schedule prepared weeks before, it would be irresponsible of Aichan to leave her two friends there to "immediately take a flight back" for the concert. Their scheduled flight arrived in Japan in time for them to attend the concert, so that part of the "report" is an exaggeration of the facts.