Ok, new balls are introduced and discontinued all the time in the bowling world. They say it's good for business, but I disagree.
You have a ball (ball a) which you love. It does XYZ very well. Ball A gets eaten by the big bad pin setter and management can't find any more ball A's around. So Mr Pro shop guy says "The owner says pick a ball that's similar to what you had." Which factor of ball B is the most important to you? The biggest sticking point? Do you wish you had the same core shape, or maybe you liked it because it was low rg high diff, etc etc.