I think the closer the DS is to a cell phone, the more Nintendo misses the point.
The DS is a hand-held gaming platform. It's the perfect way for the average consumer to get into games, and for the casual gamer to delve into more hardcore offerings.
More gamers means more software sales.
Nintendo needs to focus less on the actual hardware (which is fine the way it is) and focus on making software that encourages people to get into gaming; titles that range from the almost-non-game-casual to the this-is-serious-business-hardcore games.
Those casual-turned-core gamers can then expand their experiences with more "traditional" consoles like the 360 or PS3, which is definitely a good thing for the gaming business.
So, Nintendo - we don't need no stinkin' NintenPhone; we just want more games to play on our DS.
Only then can we start on our Crusade to convert all the world's people to the gamer's way of life.