Don't forget the worst offenders of all time in the "end of the road" scenario for a line: The last three waves (one for C1, C2, and C3) in 2000 for Episode I and, more notably, the last POTF2 EU wave of the Space and Darktroopers in 1998. Hasbro does not have a good track record for these things to say the least. Let's take a look back for a moment:
-Final POTF2 Collection 1 wave (1998): Prune Face, Boussh's Bounty Chewie, Lobot, and Mothma. Anyone who was around at that time remembers how hard these were to find. As it was, I never saw them at retail and only had them because of JCPenney selling a four pack in their Christmas catalog that year.
-Final POTF2 Collection 2 wave (1998): Spacetrooper and Darktrooper from the EU line. Enough said.
-Final POTF2 Collection 3 wave (1998): This one can go two ways, but neither looks good. The last actual C3 wave to show up at retail was Ree Yees and the Death Star Trooper, and they were impossible to find. The last actual wave of C3 was the FC4 of Snitkin, DSD, AT-AT Driver, and Hoth Leia whose placement there was because retail was sick of Hasbro shipping the same crap over and over and leaving them stuck with a mountain of Rancor Keepers for months on end.
-Final POTF2 wave (overall; 2000): Admiral Motti and Princess Leia in the CommTech line.
-Final Episode I Collection 1 wave (2000): Swimming Jar Jar, Battle Damaged Destroyer Droid, and Jedi Master Qui-Gon Jinn
-Final Episode I Collection 2 wave (2000): Pit Droids 2 pack, Sio Bibble, and Ascension Gun Amidala
-Final Episode I Collection 3 wave (2000): TC-14 and R2-B1
-Final (non-sneak preview) POTJ wave (2002): Bo Shek, Teebo, and R4-M9
-Final Saga wave (2004): AT-ST Han, General Madine, General Lando (to Hasbro's credit, all three were immediately reissued in the OTC line)
-Final Clone Wars wave (2003): Pilot Saesee Tiin, Mon Calamari Kit Fisto, and SA Clone Trooper
-Final OTC wave (2005; technically post-OTC): Dannik Jerriko, Myo, and Feltipern Trevagg
-Final ROTS wave (2005): 501st Legion Clone Trooper, Holographic Plo Koon, Holographic Aayla Secura, R4-P17, and Wookiee Heavy Gunner
-Final TSC wave (2006-2007): Commander Appo, Combat Engineer Clone Trooper, Kashyyyk Elite Clone Trooper, Holographic Obi-Wan, Arena Padme, Darth Vader's Astromech Droid, and Yarael Poof
Outside of some of the last TSC stuff (Padme and Poof, I'm looking in your general direction), nearly every figure I've listed above in these lists has become highly sought after for one reason or another, with the biggest reason being that Hasbro hardly shipped any of them and stuck them at the end of a dying line rather than give them prominent places in their next, more widely shipped lines. That's why when Hasbro swears up and down that the tons of Greatest Battles/H&V figures clogging everyone's WMs has nothing to do with the stores getting more basic TSC figures, I do nothing but laugh. Sure, they might have different UPCs, but to the stockers, it's all just SW figures and as long as the pegs are full of Padmes and Threepios, there is no reason to order or stock anything else, different UPC or not.