It is possible to have elevated blood pressure during the progress of aortic stenosis but the ultimate result is usually hypotension when the pump starts failing and becomes unable to overcome the huge gradient.
This is why it is unlikely to see a symptomatic (angina, syncope and CHF) aortic stenosis with elevated systemic pressure.
We don't see patients with terminal stage aortic stenosis that frequently anymore since the threshold for valve replacement has been lowered significantly over the years. This is why many physicians have not really seen the natural progress of the disease and what happens during the final stages.