Masahiro Sakurai:

• Having his own company he has the management experience
• Extensive experience with Nintendo
• Friend/former colleague with Iwata
• 10-15 years younger (born 1970) than most anyone in Nintendos board of directors
• Can endure extreme workload (Smash development)
• Understand social media
• Understand modern gaming.

I've kept silent out of respect for Iwata on this subject, but now that it's been a day, I will just get one thing out of the way before I contribute. For a thread to pop up with a title and OP like this within minutes of the news breaking, insinuating that Iwata was preventing Nintendo from coming back in full force is, IMHO, insensitive, and a despicable show of disrespect. If the OP actually had any interest in the man and his health and its impact on the company, he would already have known the dire outlook for bile-duct cancer, he would have figured the likelihood that Iwata and Nintendo might already have prepared for this eventuality. Moreover, if the OP has any knowledge of business sense at all, they'd know that succession planning at all levels is a common standard in business.

Although I don't agree with it, I understand the logic behind the moderators' decision to keep this thread open, despite many saying that posting it was too insensitive, and too soon.  But it's a fact of life that mod decisions of any site can end up representing the stance of the site as a whole, intentionally or otherwise, and I'm afraid that for a few hours that particular mod decision looked far from good. Fortunately, that has been balanced now by the gracious act of honouring Mr. Iwata through the changing of the VGChartz logo.

Back on topic.

Nintendo haven't named an interim president, but from their notification of personnel change it's clear that Miyamoto and Takeda will continue in their positions in the meantime until further announcements are made.

I'm of the feeling that they might have someone younger take over, so that there's a longer tenure, since both Takeda and Miyamoto are in their 60's. A couple of years ago Miyamoto was talking about retirement. 

A very likely candidate I just hope it doesn't disrupt NOE's good flow in the last decade as they improved massively, this is the guy essentially responsible for localizing games like Xenoblade and Project Zero.

he is really a good candidate and hope he knows what is needed for NoA. which is games intended for western audience.

As sudden for us it was, Iwata could be aware of what was happening. Thus, he may left something for this question.

Surprised no one has mentioned Eguchi -- the guy who was the lead producer on WiiU hardware and oversaw EAD projects like Mario Galaxy and Mario 3D World. My impression is that he's pretty much in charge of the Tokyo office.

In any event, we pretty much expect some Japanese guy who's been with the company since the 80s.

I have little doubt that there are many potential applicants for the job.

Let's be honest, Iwata had some magnificent personal qualities HOWEVER did lack some finesse in actually running the business. I've loved Nintendo's independent direction, but I'm tired of the go-it-alone behavior.

Out of all the canidates, I'd say these are the most plausible towards continuing Iwata's legacy and expanding upon it: 

Masahiro Sakurai: Similar to Iwata, he was a game developer under HAL Laboratory, president of Sora LTD, and if selected, would be around the same age as Iwata was when appointed president back in 2002, which means fresher ideas in addition to what is already established. He has great overall communication skills with the gamers, but is quite wary of leaks and might lack the drive to run the company.

Genyo Takeda: A veteran at Nintendo, he was the company's first game developer who also pushed the company foward back in the 90's and early 00's. However, he has been opposed to trying out new technology, which would hold back Nintendo even further hardware wise. At the age of 66, he might not want to try innovating outside his comfort zone.

Satoru Shibata: Former president of Nintendo of Australia and current president of Nintendo of Europe, he has had experience outside the japanese fanbase which can mean better communication towards the western branches. He has exceptional mannerisms similar to Iwata's humble and kind ways and has also been in several Nintendo Directs. Overall the most likely groomed canidate, he might not have a strong connection with gamer's tastes and preferences.

Unlikely Others:

Shigeru Miyamoto: A game developing legend, he has admitted that he isn't suitable as head of company, as he is far more engaged in the creative side of management. 

Satoshi Tajiri: Creator of one of Nintendo's most reconized franchises, he is currently working under Game Freak as Executive Producer. Might be a stranger to the management side.

Reggie Fils-Aimé: No stranger to the management side of business, he could theoretically bring a western flair to the company. However, it is evident that he does not speak japanese, which is elementary when running a japansese company in the heart of Japan.