There is only one absolute when discussing Apple's future plans, and that is that absolutely no one knows for sure what the hell they will do next...even Apple themselves don't always seem to know. Their cult of secrecy and surprise is a massive part of their allure and success. The only "never" anyone can reliably assign Apple is that you "never" know what they'll do. Period.
I, for one, could easily see them packaging a few basic options of the sport model on sport straps for sale at Best Buy, Target, etc., to cater specifically to the segment of tech-aware but budget conscious market, who have no interest in steel, bracelets, gold, etc, but want a piece of the Apple cachet, and don't live near an Apple Store. That is to say a HUGE swath of America.
If the slowdown in watch sales that the tech blogs have been reporting is accurate, I'd wager we'll see at least a basic black strap space gray 38/42 offering in big box stores by Christmas.