Yeah they are, they just cannot be verified - or cannot be verified yet.
The higgs boson theory was theorised in 1964 and it was untestable at the time, but that theory got the funding together to create one of the largest and most expensive scientific instruments built to prove the theory.
Nuclear fusion was theorised in 1915, again untestable at the time, and look how far we've come.
The above comment is an anti-science comment if I've ever seen one.