Teaching to the test isn't going to go away as long as standardized tests are administered, especially when the results of these tests are reported to state bureaus, published publicly, and integrated into teacher evaluations. When the funding, public reputation, and the job retention of teachers are all on the line, it doesn't matter what kind of test is given. Curriculum content and teaching methods will conform to the demands of the test above all other considerations. Administration will remain fixated on test results, and quality, home-grown assessment will become a footnote.
The testing culture will continue to affect textbook selection and vise versa. Put simply, the textbook industry is thoroughly Common Core. Schools must insure that their texts leave no gaps in testable information. This has driven the textbook industry to design texts that cover all the Common Core bases. It is nearly impossible to find recently published textbooks that aren't structured for Common Core testing. Once schools are glutted with these textbooks, classroom content will naturally undergo a Common Core evolution, thus pointing schools toward Common Core tests. Alternative testing agencies are bound to adapt to the new market by giving their tests a Common Core makeover.
The whole point of standardized testing is self evident: to align instruction to state and/or federal standards. They're not for schools to self-evaluate, but for states to measure whether content and outcomes meet bureau expectations. School and district leaders are, in turn, supremely interested in whether curricula are designed to maximize performance on external measures. By definition, standardization creates an environment in which deviating from the norm is risky.
Public school regulation is a given, but let's be honest about implications for parochial school districts as well. Whether Common Core is the program du jour or a hybrid state formula, regulation is regulation. Parochial schools that opt into state regulation have less control over their curricula because they have inserted a third party authority. This is not to say that regulated parochial schools have NO control over content, methods, and assessment. However, even the least intrusive state regulation has a bottom line--namely, demonstrating that expected state practices and outcomes are observed. When hundreds of thousands of dollars in vouchers and other subsidies are on the line, toeing the state line becomes an imperative. This is a departure from the autonomy that has, in part, effected superior academics and virtue development for parochial schools. Families seeking shelter from the educational trends that drive public education policy stand to find fewer genuine alternatives.