Hi 'jt' -- I've spent (wasted?
) so much time studying and trying to fully understand this part of eBay policy that I think I can answer your question.
Referring only to Canadian sellers, there are currently three different TRS designations:
1) TRS Global, where, amongst the other criteria, you need to maintain the 100 transaction per year volume and Bronze Power Seller status. No tracked shipping required. This gets you the badge on .ca only, and the 20% FVF discount regardless of your status vis-a-vis eBay.com.
2) TRS U.S. -- this is based on essentially the same criteria as Global, but you must maintain the 100 transaction level on sales to the U.S. only. No tracking required, but you don't get a badge on .com (you'll still have your "Global" badge on .ca though). You will get the 20% discount, but since the Global designation gives you this anyway, I think U.S. TRS is meaningless to Canadian sellers in terms of the discount. However, it does (so they tell us) apparently give some advantage in Best Match visibility.
3) TRS Plus (U.S. only) -- This is the one that, in addition to other criteria for U.S. sales, requires validated tracking for 90% of shipments. It gets you the badge on .com and (so they tell us) better placement in searches. I had the TRS Plus badge showing on my listings up until the Aug. 20th evaluation when the new tracking requirements came in and I decided to let it go. I'm really not convinced that having that badge displayed was making any significant difference in sales, especially not after the debacle in May of this year. It certainly wasn't worth paying for tracking on every item I sold to the U.S.
I suspect any Cdn. seller who gets the message you received is close to the brink of losing the regular U.S. TRS, usually in terms of volume (number of transactions), which is essentially meaningless. I've been getting little warnings on my dashboard under my US TRS status about my U.S. transaction volume running close to the line. However, losing US TRS won't mean you'll lose your 20% discount -- that will still apply as long as you continue to qualify for Global TRS.
In other words, to make a long story short, that message is just eBay trying to make itself look supremely generous by giving Canadian sellers something that most probably don't need anyway -- a prettily wrapped gift box with nothing inside. 
Yes, you're absolutely right 'poco' -- I was going to include some explanations about TRS on other (international) sites in my post above, but decided it was already sounding too complicated, and that most sellers would be interested primarily in US or Canada.
Thanks for the additional notes. At least it didn't all come from me -- people already think I'm too long-winded.
