I spend a lot of time reading here but this is my first post. This is probably because everyone is usually so thorough there isn't anything left to say:)
If you have two WiFi cards bonded you would have to consider one additional thing and that is how WiFi communicates at layer 1. I'm sure you have seen the settings CTS and RTS in routers and WiFi cards before(This may improve your performance in itself). They are acronyms for ClearToSend and ReadyToSend respectively. This is generally used in networks with nodes far away or a crowded channel or for whatever reasons have a weak/unreliable signal/connection. It allows the sender to basically ask if it can send and receive confirmation (best effort) that its OK to send its data. Only ONE and only one WiFi card can speak in a channel at a time. This includes not just your network but ANY network on the same channel that can be seen by the card. If it is not OK to send and the card tries to, there will be a collision similarly to how Ethernet hubs get collisions. A collision results in BOTH parties needing to resend their data. Effectively this has not only wasted the time of the two colliders, it also wastes the entire networks time as they had to wait, Will have to wait again when you resend AND it was all for nothing. As is this will not improve anything I believe because either the only one card will xmit at a time or both will and this will horribly reduce throughput.
What you 'may' be able to do is take advantage of a multi-band router that has to discrete antennas (4 really. Two for send, Two receive). My thought is you could place one on a 2.4Ghz connection and the other on a 5Ghz. I don't however know the requirements for teaming WiFi and Ethernet really doesn't have anything I can even compare that to so the OS may not let you even do that. The router really must to have the two antenna, separate and be able to send/receive simultaneously or there will still be no real advantage as its still one card talking at a time. You will still be on the same sub-net because the router bridges these to together on its side. Bridged. Not bonded or teamed but sometimes trunk'd. (I'll explain about trunk'ing at the bottom.) All 3 (bridged/bonded/trunk'd) are totally different unrelated things.
Also there is two types of bonding. Layer 2 and layer 3 bonding. 2 combines them at the mac address and 3 by a common IP. I honestly have no idea how WiFi determines destination at layer 1 in order to pass it to layer two so I cannot even guess how this would work even if you are using two separate channels. If I had to take a guess I would definitely be less then hopeful about the results of trying to team WiFi cards. I think at best you would see no improvement. At worst it won't even function. I'd love to hear how this ends up working in the real world. Anyone done this?
Lastly, "port trunking" is NOT nic teaming or bonding. Port trunking is when you are using vlans and you are connecting to switches (layer2). Basically only vlan tagged traffic, other than traffic on the default vlan, will go across this link. It's a trunk of vlans. It is true though that people often bond the nics at either end of the trunk because of the bandwidth needs of several to many subsets going across one physical line regardless of the virtual separation a vlan provides. This is a separate configuration however and in no way a requirement (or a best practice.) for trunking.