I'm probably one of the odd balls who is indifferent to these potential changes. On one hand, if I'm travelling internationally it is typically for business where my company allows me to book J to Australia or PE to Europe - the only two places I go non-domestic. If SWUs to J could only be used by booking PE then this would probably help my chances to Europe. Now on the other hand, if I was going to pay for a personal vacation to Europe I'd say this would hurt me as I'd be bringing the wife so I couldn't shell out the price for PE. I'd probably still burn the SWUs in that situation as PE is better than Y.
The miles devaluation is disappointing but I can't say I'm surprised. I have quite a bit of miles these days and we typically shell out miles for 1-2 trips somewhat close (Caribbean, Mexico, Hawaii). If there are cheap F fares I'd grab them but for these flights we normally just book Y and hope for a nice MCE seat. What is crazy to me is the price for international J award flights. I looked to bring my wife with me when I had to go to business for either Australia or Spain. The miles to get her in J is ridiculous.