There are 50 days until the Pac-12 returns as an officially recognized conference with nine schools for basketball, eight for football and one lingering, inescapable question: Will it expand again? Conference executives have acknowledged that an additional all-sports member would create the ideal size. But when the issue surfaced recently on two campuses, Washington State and Colorado State, responses from key voices hinted that further expansion is unlikely. That the value proposition is unwavering. That the standards are lofty and the options limited. That remaining lean and nimble is advantageous within a roiling landscape. “We are building a new brand, which is both unique and very powerful,” Washington State president Elizabeth Cantwell said last month during a news conference to introduce Jon Haarlow as the permanent athletic director. “Any additional schools would have to be ready for that brand. We operate really tightly. … You don’t see that really anywhere else.…