I don't want to turn this in a console fight (I also own all Nintendo consoles since the NES, except for the Virtual Boy) but I can't understand what you wrote about SEGA.
Have you ever played SEGA in the arcades or at home before the year 2000?
SEGA arguably did some of the finest arcade games of all times, not just the software, but also the associated high-end arcade hardware with moving parts etc.
Their consoles (except for the 32X and then the Saturn in the West/outside of Japan flops) and software titles were mostly great, especially the arcade conversions.
Their last effort, the Dreamcast, was a particularly interesting console in my opinion, especially considering its short lifespan. Others already mentioned titles like House of the Dead, Sonic, Shenmue, Phantasy Star...
The Dreamcast was ahead of its time (online gaming on consoles with player avatar and stats, VMU hardware in the gamepad, basically a precursor for the second screen mantra used today) in my opinion.
SEGA just never had the financial stability or cash liquidity mattress to sustain losses as Nintendo (still) can, but the writing is on the wall for Nintendo long-term.
They either launch new business units (eg. theme parks in Asia could be an idea) or pull another original-Wii-like surprise rabbit out of their pocket soon...
I don't see much of their IP working well on iPads or tablets because of the traditional control schemes. Some IP like Pokemon might work fine.
The problem with Nintendo is they are slow to react to changes, which is a problem in today's world with yearly HW cycles on tablets and smartphones.
They correctly identified Apple as a new competitor in 2010 but didn't act on it (at least not successfully), same for attracting more third party content on the Wii U, that was already a problem on the original Wii and before...it's 2014 and both problems are not resolved.
Nintendo could very well be forced to do a SEGA move a few years from now (or someone buys them out, but given their company shareholder structure and Japanese corporate laws this is next to impossible).