All of your points seem fair, but I'm wondering, how does this all apply to Japanese mobile phone companies? It should be much cheaper over there, should it not? 

would be a nice feaeture, but Iv never used a 3G device, how does it work, like Wi-Fi?

Depends on how they would implement 3G. If it were just for the lighter features of the push service, it could be miniscule, just to help keep you connected, tweets and such.

It would be nice, however, it should be free of charge or at least with a small fee to Nintendo, because having to pay for other mobile market companies would suck a lot to me.

Could it replace cell phones? Teens and people now a days txt more than they talk. If the 3DS connects via 3G access, then a program like yahoo messenger where you can txt to cell phones (SMS) free could really be a hit for Nintendo!

If its online has 3G connectivity 3DS will most likely be bigger then ds.. Now DS competes directly with all other handhelds, except phones

On the one hand, 3G support for upcoming online mobile devices like the 3DS and PSP2 makes incredible sense, but on the other hand, are you gonna have a fee for every device?  Seems like you wouldn't want to pay for it for more than your phone.

That's actually why I hope the PSP2 *is* a phone, so I can just use that in place of another smart phone.  I'd get more use out of a mobile PSN than any app store, I tell ya that.  Not sure if I'd be willing to pay for 3G for something else on top of that though, if I could even afford it.

As more and more devices start using 3G, they're going to have to come up with more general data plans that span multiple devices, or else the devices will cannabilize each other's sales for those who can want or can only afford one fee.

its NTC DOCOMO 3.5g/4gb so likely GSM, verizon its out. since their cdma its not worldwide

they are going to close emself in the US. they like going GSm becasue of that utms and it succesor.

I had considered this, but it ignores the current universal business plan for DD games which means selling downloads at the same price as retail.

If you think Nintendo is willing to cut this very profitable aspect of DD games "for the convenience of the consumer" I think you're mistaken. The only way they can continue to sell DD games distributed via a pay per data unit agreement at the same price as retail, is if they eat the fee being charged by the 3G network service provider, in effect making DD distro less profitable than it currently is to every other DD provider.

What Nintendo charges for 3G access (per data unit being the most likely rather than by subscription service) will largely depend upon the conditions of any deals they make with 3G network service providers. Any service through Nintendo (having no 3G network of their own) would be effectively "rented" from the 3G network provider with those costs being passed directly to the consumer.

It functions much like Wi-Fi, but rather than being a local network, it functions like a super wide area network (coverage similar to cellular coverage) only at much slower data transfer speeds than any WiFi network.

The other downside of 3G network devices is that they require data subscription plans, which are generally $30 in addition to the monthly phone service/text service fees.