Making the best guess, what do we think the rate will go in the next
three years, and the next four years? I realize it's up to the Fed but
I'm looking for a good, informed guess based on the past and some
broad predictions of how the economy will shape up. I.e. if the "worst
case" is the fed will raise the rate by two points a year, that would
put it at +6 pts in 3 yrs, or 10.75%... thanks, Eric

I'm not smart enough to guess the Prime Rate in 4 years.  But you
might consider hedging the risk at the current level of 4.75%.  In
that manner, you would be indifferent in 4 years;  whether the Prime
Rate was 6% or 13% would make no difference to you as you would be
"locked in" at 4.75%.

Such hedges can be accomplished using derivatives, swaps, futures,
forwards, options, or the mutual fund RRPIX.  Caution:  you should
consult with a professional.  Otherwise, you might blow yourself up.

Good luck!

Thanks for the comment. Yeah, I'm not sure how to use any of those
mechanisms you mention to hedge ;-) My specific situation is that I
have a HELOC set at prime - .25%; I need to loan my business some
money but I need to lock in guaranteed monthly payments. Since my
HELOC is adjustable but the payments have to be fixed, I figure I'll
estimate the "worst case" and then base the monthly payments on that
rate... I just don't want to loan the company the money at 5%, and
then have the prime leap up to 8% next year, leaving me in the red on
the loan.