one size wont fit all?
you say one size fits all is hard to come up with, hell they only want to have the option of wifi/cellular access, one, two or three choices, its not hard to see you provide both functions and let the user disable one or the other, or enable both.
Its not beyond the technology now to build both a wifi card, bluetooth and a gsm card into laptop and that about lets it connect to anything.
Drop in a wired modem, a wired network, and a 9 pin serial port and what cant you connect to?
Its all established proven tech so no need to bump the price up.