His last maybe. Nintendo is not just gonna stop making them.lol

Well they found people for Mario and Zelda, so Im sure they'll be ok.

Didn't he already said that on Smash 4?

He did. But with ultimate and bringing back the old fighters, it looks like a good time to pass the toarch.

Maybe HIS last one. But there's no way Nintendo is just going to let these games stop. They likely have had discussions with Sakurai about a potential successor who can take over his role as Director and Game Designer to ensure the series continues without missing a beat. When he left HAL Laboratory, they didn't suddenly stop making Kirby games. The puffball kept going on without missing a step.

He said the same god damn thing about Smash Bros. 4. He'll be fine.

http://www.nintendolife.com/news/2014/12/masahiro_sakurai_admits_that_super_smash_bros_for_wii_u_may_be_his_last_in_the_series

He says that for the last 2 or 3 Smash.Plus, even if he dosent direct it, he will be involved in some way with the next one, and the franchise will keep on going.

...Honesty? Probably a LOT of people. As gamers we really like to fetishize the few gaming directors we follow and know about (Cory Barlog, Kojima, Sakurai, and a long time ago Peter Molyneux). In reality, there are a ton of staff that for one reason or another are just not as well known, who probably have the talent and capability to do what Sakurai does. Smash is actually one of the only games where I could see someone making a point that Sakurai is integral though, because people always make it out as he's the only reason third party characters get into Smash. I know that's true for say Snake, I don't know how true that would be for other fighters though. Either way I really do think Smash could continue quite easily with Sakurai. 

He ALWAYS says that. lmao.

Well, if this is your last, then he left it at the highest point. Gathering all the characters that have participated in the series is simply amazing. I do not know if there really is another fighting game that has such an incredible roster. This game is going to be legen - wait for it - DARY!