Why is it that people never seem to get that retailers are not Canon and an individual retailers pricing decision often occurs independent of Canon (or any other manufacturer).
Fact: Canon is not offering the EOS M for $299.
Fact: There is no rebate currently offered for the EOS-M, which means no enforcement of minimum advertised pricing.
Fact: B&H offered the camera for $299.
Fact: We don't know why B&H made this offer.
Fact: Adorama and Amazon are major competitors with B&H.
Fact: Adorama and Amazon matched B&H's price.
Fact: We don't know why Adorama and Amazon matched B&H's price, but we can speculate it has something to do with the competitive marketplace.
Fact: Eventually, the EOS-M will be replaced.
Assuming any relationship between the last fact and all those preceding, without correcting for all of the other variables, is simply sloppy reasoning.
Have you ever investigated "dealer incentives" that car manufacturers offer to their dealers? The price reduction could have come about because Canon let it be known to its retailers that it had a warehouse full of M kits that it was willing to sell to them (the retailers) at a much lower price and B&H, being B&H, was the first retailer to reduce their price in response. Dealers don't typically sell stuff at a loss without good reason, even if their competitors decide to.
Even if the M is being replaced, the retailers could simply hold onto their current kits and reduce their prices to the break-even point when the new model appears. Given Canon's pricing history, that break-even point is likely to be well below the price of the new models' kits.