It'd really be nice if CEOs dropped the schoolyard attitude and got back to actually trying to run their companies.
Steam and OnLive really aren't even directly competing. They're in the same industry but offer two different products for two different kinds of people. Steam customers are not OnLive customers due to lag/graphics and OnLive customers won't be Steam customers due to hardware restrictions.
OnLive is just as much a "monopoly" as Steam is, because they both offer a type of product that no one else is offering with their success rate. Neither really have that firm a stranglehold on those industries. The cloud gaming arena is still wide open, OnLive just put their foot in first. A competitor with better capabilities could easily overtake their sales. Steam's real advantage is that they have plenty of high profile devs supporting them. Steam's sale prices are great, but can you say the same for the "normal" prices? When I buy a game from Gamestop, I'm also paying for the disc, packaging, manual, employees and business expenses. Steam has business expenses of their own, but should a digital-only copy from them cost the same as a packaged retail copy? I think if another business could get PC devs behind them like they back Steam, they could offer cheaper base prices and give Steam some competition.
The real monopoly here is the business model that both services compete against, brick and mortar stores. Buying all the competition out and using their names as puppets, then fixing all your prices to lower the buyback rates of used products, that's a real monopoly. Gamestop will not be missed.