Even if these steering currents don't change much, I'd still expect the hurricanes themselves to be noticeably more powerful and possibly more numerous. My guess would be an average of .5-1 category stronger, on average. This is in line with my own personal suspicion that we'll see a couple of degrees of additional warmth observed in sea surface temperatures due to global warming from now on compared to decades past. That's a big deal in terms of available energy for storms to form, organize and grow.
Similarly, I'm expecting to see more tornadoes in my neck of the woods for similar reasons of additional available heat. Weld County, CO is just east of here and while it isn't customarily thought of as part of Tornado Alley, the fact remains that it holds the record for most tornadoes recorded in any county, worldwide.
Global warming is already being felt here as a general movement of climate bands to the north such that the climate familiar to the northern New Mexicans of my childhood is now experienced here in northern Colorado, and I'm betting it's bringing Tornado Alley with it.