In terms of performance, while it CAN be done, it would be several orders of magnitude slower than even the slowest phones on the market today.

I'll just take the processor module as an example: in a modern consumer processor, bidirectional bus speed to the CPU can be upwards of 25.6 GB/s (gigaBYTES) - compare that to the 50 MB/s typical speeds of your average 802.11 network. It wouldn't even make sense for the phone to have RAM when using such a slow interlink as it would be no faster than flash memory.

Yes, it CAN be done, but it would be so slow as to be unusable for most purposes.