What are (or could be) the dangers of wifi only devices?

I'd say that since there is no such thing as a 100% libre mobile device, the entire device is corrupt from the beginning. There's no way to be certain of what every part of the phone is doing so it is an inherent security risk.

Replicant is trying to fix this as much as possible, but even running a libre android distribution won't necessarily be enough.

On a side note: Firefox OS (B2G) seems like it may be a viable libre alternative in the near future.

Cell phones are pretty fundamentally broken security-wise right now. The sad thing is that even using fully free software doesn't necessarily fix all the problems. Standard GSM encryption for cell phones is broken, see here for details. So free software that interoperates with existing cell phone technology wouldn't be able to fix that. And it's going to be a very long time before that's fixed--GSM is frequently implemented in hardware, so the only way to fix that is to replace the hardware.

Gnuser

You ask: What are (or could be) the dangers of wifi only devices?

Here is my 2.5 band penny question to you?
What is WIFI?
What is a secure WIFI connection?

Dude! I'm sorry but you need to search for correct answers on the net, since everybody have different opinions or want to sound intelligent with their answers.

In my opinion, all depends on what you are looking for and use..

Thanks for all the replies.

Well, expanding in my original post:

Cell phones are not secure because even from a hardware perspective the modem (which is closed source and kinda like a black box) can access the microphone directly. That allows the police and well connected crackers to spy on people at will. So, using a wifi only device (which means, a tablet or a cell phone with an erased modem) is a better solution. Even more, if you destroy/remove the microphone you are defending yourself even further (you can always connect a mic in the plug in jack if you need, and I am actually thinking of a little device that could be used in smartphones, as soon as I get something working I will post it too).
However, aside from the whole "audio spy" things, I wonder how much using and Android device with free software and proprietary firmware and drivers can be dangerous. What are the hardware disadvantages of these devices (how much the proprietary firmware can be used against the user for example) and how much the software can secure the user (for example, how much using a firewall can actually prevent the device from making some connections if those are triggered by the firmware or the drivers for example).
On a different note, we all know that a computer with free bios is better. For example, if you set a password in a proprietary BIOS there will still exist a "master password" which does not happen with libreboot for example. In this regard, what is the closest thing we have right now for tablets and such?

And what Firefox? Someone mentioned this but I know close to nothing about it, so, if someone has more knowledge, does it makes us freer/safer?

Thanks!

Addon to my post above: why do we have libre drivers for hardware in pcs and not in tablets?? Is it really that different? How much hard would it be to run Trisquel in a tablet for example?