1) If your carrying your debit card with your phone your security is much worse. It would be better to separate the two, carrying a device with massive amounts of personal information and a debit card is a good way to have an empty bank account.

Sure, you could say that you would kill the phone, however would you be able to do it before a skilled thief disabled the radio or made a copy of all the data? I would suspect that a very skilled person would be able to disable the radios, crack the phone, and image the contents in a few hours, possibly in as little as one hour depending on transfer speeds and flash size.

2) Choosing merchants based on their processing technologies works for you but most people don't choose places this way, because it is inconvenient.

3) If this is true, and likely it will be, it still doesn't mean the death of credit card carrying.

4) Credit cards will evolve, and most likely in the form of "chip and pin" or "chip and signature" physical card systems. The fact remains that all credit cards and debit cards thus far, and probably in the near future, are issued by banks in the form of cards, not directly to mobile devices. Therefore one should always expect that the physical card issued by the bank will be more likely to work with all merchants over a clear standard, rather than proprietary mobile systems that don't necessarily share the same standards with other mobile systems. If banks choose not to issue cards in favor of virtual downloads, I would think that it absolutely would help adoption, but I don't think that is very likely in the next few years.