Other things to consider also is we've had the time to consider whats going to be rotating out at the end of the season. At the beginning of the season, I made sure to warn my league players that there is the potential of losing tons of cards at the end of the season due to formation, and that if they're not certain they want to play Deck A (Lets say Luxchomp), to make sure to get their money's worth for it for the supplies they need before the season ends, or before a big tournament where the demand is higher. M:TG goes through a format shift yearly like we do, though its known every season what gets rotated out. People playing M:TG still use what's good for their Grand Prix to the end of the season, even if it came from the first set to get rotated out. (During Ravnica/TS block, there was a ton of Ravnica based cards still around for the end of the season. Expensive dual lands, come to mind.)
I run a league with a lot of younger kids who don't really get the opportunity to spend a lot of money and as such can't build the big competitive decks. Now, once again, everyone in my league is at an equal playing field and I can see a lot of fun that they're going to have now that theres no longer the potential of them challenging one of the competitive players and losing on turn one, especially since many of them have been buying HG-SS on packs and have the trainers/supporters they need to bring them into this new format. I feel for those of you who have leagues that cater to a competitive fan base with players who will be disheartened by this change, I really do. But if you can show to them that life can and will go on and be positive in the light of what you think to be bad, your players will see it to be not such a bad thing and can handle this shift a little better. Remember, there is still some time to sell now before the shift does/does not happen.
My thoughts in your sense turn to a competitive family that I brought into this game last year who's son just made his first Top 4 cut in Juniors at Regionals and had all his supplies for Luxchomp. I did just call her a little while ago, and she's just as excited for the format switch as I am, though a little annoyed by the suddenness of it, however she still will be making the trip out, whether the format shifts or not, so this may not be as bad as you think. Honestly, just take the shift with a grain of salt. All will be all right, and the format will be so fantastic. :3
Also, take into consideration that P!P may not simply be JUST looking at Sableye when it comes to this possible shift. Other factors may actually be decks like Luxchomp, Dialgachomp, SableLOCK, Gyarados with the Sableye engine, anything with Crobat G or Uxie.. Just any of this in general could shift the format. I encourage you to play whatever you want, since most of the decks that will be seen will still utilise the same cards that Pokemon may be looking to remove in general. (All of the important gems come from within 3 sets of each other. LA, SF, and PT), so if you want to play Sabledonk, play Sabledonk. If you want to play Gyarados, play Gyarados. If you want to play Luxchomp, play luxchomp. Honestly, I think all of these decks in general will get the point across.
So glad I got out of this game, HG/SS-on is going to be the most boring format ever.
Yeah, its not like there isn't 4-5 possible decks in meta already that look to be good, or 2 sets coming out before cities next year that could make other possibilities. Such a boring format. You go have fun with whatever it is you're doing now, its probably far less boring than not playing Luxchomp at every event.
. Nobody plays with older cards because they can't buy them, there's no more support for them, and the players collect newer cards so finding those older ones become significantly harder to find. It discourages players who see deals at Target and such, buying blisters of two HG and now can't use that platinum pack or arceus pack at all. The Clash of Legends sets released recently are also utterly useless, and anyone who traded for a not-so-meta deck like Arceus or the blisters with the full Charizard line have essentially wasted their time.
This is why you support your mom and pop hobby shops. I run my league at a model plane/war miniatures store that also profits from both Magic and Pokemon being in its store. Any set that he can order that is requested by my league, he will buy for the league because he can profit off of it. Target/Wal-mart/etc only give you the most recent sets, and older sets that aren't bought any more due to not being in demand.
I do also agree with a lot of you in wondering why we couldn't just have the format shift now. But I do think this little break between gives the sellers some time to pawn off their wares before their cards are completely useless.