Apple’s new iPhone 5c and flagship iPhone 5s debut on Friday and there is much debate surrounding opening-weekend sales. Apple made the iPhone 5c available for preorder last week and sellouts have been beyond scarce, leading some to believe demand is weak relative to previous launches. Meanwhile, reports from half a dozen sources including an exclusive BGR report suggest iPhone 5s supply will be severely constrained at launch, potentially putting another damper on debut-weekend sales. Despite all that, one industry watcher believes combined 5s and 5c opening-weekend sales will crush Apple’s previous record, potentially reaching 8 million units by Sunday night.KGI Securities analyst Ming-chi Kuo nailed just about everything there was to nail ahead of Apple’s iPhone 5s and iPhone 5c unveiling. Now, he’s back with a new research note picked up by Apple Insider and he projects that Apple will sell between 6 million and 8 million 5s and 5c handsets combined by the end of this weekend. Even at the low end of Kuo’s estimates, Apple would top opening-weekend sales of last year’s iPhone 5 by a healthy margin.As it did with the iPad and iPad mini this past November, Kuo says Apple will likely announce combined sales of both models rather than individual sales figures for each. If nothing else, analysts will have some fun estimating the mix — and Kuo got a head start. According to him, the flagship iPhone 5s will account for between 35% and 45% of total opening-weekend sales while the slightly less expensive iPhone 5c will make up between 55% and 65% of sales.