Like crunchyg stated, Mario in general will be a progressive innovative phenomenon if Miyamoto supervises it. Because a trend I see when most iconic directors/producers retire is that the prospects often try to do a new approach that may not impress fans at all. And when it comes to the generations, people will obviously be into the cyclical process of the franchise being the epitome of the platformer genre.
There’s a lot a history in Mario where you see that he’s smooth with the ladies (you have to go really retro into research to find that out) to a guy that can exist in other game multiverses (i.e. Sonic). And although people may worry about oversaturation, and whether or not the downfall will ever come to fruition, I think it will be a long time until that happens.
It just feels weird to contemplate on the end for characters like Mario. It feels as if a part of you was stripped away, and there’s nothing but an unsatisfactory void that continues to grow. And what’s even crazier is that people often take for granted of characters like that, and they try to put in wildcards on how they may be descending from their thrones as iconic video game characters. But should that ever happen, they will end off to where there will be a global acknowledgement (and potentially riots).
I think because of the fact that Nintendo can get into cyclical trends, and attempt to innovate has always been a useful rudiment for them to go for so long now. And as always, they're really cash crops that can cater to a myriad of audience types.