Just a week after Walmart’s interest in smart TV manufacturer Vizio was first made public, the US retail behemoth has gone to check out – announcing it will be acquiring Vizio for $2.3 billion in cash. Following the announcement, a Vizio marketing executive slated to speak on a StreamTV Growth panel mysteriously disappeared from the virtual show’s list of speakers. Walmart’s current TV brand Onn is not mentioned in the announcement, although it is hard to imagine anything else than the retailer’s cheap TV sets adopting Vizio’s SmartCast operating system—ditching existing Google TV, Android TV, and Roku OS relationships. The loss of that partnership will not bleed Roku dry, but with Walmart’s online shopping and 10,500 brick-and-mortar stores now having…