Scott D. Miller, president of Virginia Wesleyan University, writes:  AS COLLEGES and universities look ahead to their spring terms, or welcome students back for January winter sessions, the new year of 2018 promises to be a critical one for higher education. From the impact of new federal tax legislation to the debate about immigration, these and other national and global issues have relevance to institutions large and small, wealthy or not. Most of my presidential colleagues are wary of the new year. Here’s why.