2.3.3 Other Paradigms?
There is of course an argument in favour of investigating other possibilities, at least until such time as inflation has been more directly tested. While the current suite of defect models do not look very promising, there is always the possibility of a more attractive model lying around corner.
New ideas from particle physics also have the potential for providing different mechanisms for structure formation. Exactly what will come out of string theory, large extra dimensions and broken Lorentz invariance remains to be seen. It will be interesting to see how generic the basic inflationary predictions are, and whether new twists on high energy physics carry with them new testable predictions.