Apple will release Mavericks when Mavericks is ready to be released. It has very little to do with when new Macs might be ready to be released. Apple won't hold up any releases by more than a few days for the sake of releasing things together.
It makes sense from a business perspective to do that, but I feel that Apple would delay releases by two or three weeks if it suited their release schedule. Surely last October the rMBPs, iMacs, iPads, Mac Minis and iPad Minis weren't all ready at exactly the same time? If there are new macs ready a fortnight before Mavericks is due, I think they'd hold them back to avoid having to release them with Mountain Lion and use the Mavericks GM instead.
Speaking of which, does Apple usually announce up-to-date programs for OS X when there aren't new Macs? I assumed they would have one regardless, but it looks like that's not the case this time.