If Wal-Mart decided to get in the WiMax business, nothing could stop it from becoming almost overnight the equal any of the big telcos. Buy the licenses, install the equipment, light a few more fibers, start a marketing campaign on TV, in stores, and by direct mail, and before anyone would know it, $50 billion or so in shareholder equity would be drained from BellSouth, SBC, Verizon et al, and transferred straight to Wal-Mart intergalactic HQ in Bentonville, Arkansas.
Nothing could stop this behemoth. WiMax phones? Wal-Mart sells more phones than anyone.