gaige thanks for your technical answer but RectangleEquals is not asking how to do Link Aggregation through terminal but
IF Link Aggregation can work for USB, WIFI, or other type of internet connections.
The answer is NO.
Apple didn't created Link Aggregation. It's a separated feature Unix had. Therefore Apple has zero idea how to improve it - nor does it want to spent resource to figure it out because it is not a common enough demand. Even if it wants to give you the feature it will not provide in a regular version of OS X but will provide in a server version and charge you for it.
And there are developers who can do it, by writing a lot of codes - so no free version of such application exist. You can try Connectify Switchboard for OS X.