Arduino Uno cannot upload on Arch Linux

Yes mine works fine. It is part of the UUCP group too.
dmesg on connect:
[ 232.556919] usb 1-1.5: new full speed USB device number 5 using ehci_hcd
[ 232.643491] cdc_acm 1-1.5:1.0: ttyACM0: USB ACM device
So mine uses the ehci_hcd where yours tries to use the xhci_hcd for some reason.
my lsusb:
Bus 001 Device 006: ID 2341:0010
is the same as yours, it looks like it is trying to use a different module for the usb, probably due to you having a different chipset. There are several people that are having this problem also (google: arduino xhci_hcd).
It seems that the module shites itself after about 5-7 seconds for most people, which looks to be true in your case according to the timestamps from dmesg.

One person said this helped, adding rwx permissions to the lock directory (note on arch it is at /run/lock not /var/lock) Arduino Playground - All

Upon further reading it seems to be an issue with all usb 3.0 devices and the xhci_hcd module. There is a patch in the works aparently and should come around sooner than later.

Until then what is the output of "lspci | grep USB" on your system