Never say never. There's always emulation. Almost all of the retro re-releases are emulated images of original games, be it Virtual Console titles, PlayStation and PS2 classics on PS3, SNK games on various platforms, that Irem collection published by DotEmu, every Sega Megadrive collection and so on. Panzer Dragoon Saga isn't popular enough to be re-released. If Square lost the source code of Final Fantasy VII or VIII, they'd still figure it out and release it, because the demand is much higher. Where there's money to be made, there's a way.
Raiden Fighters games got a Xbox 360 release back in 2008, along with Raiden Fighters 2. MAME support came later, around 2014. The thing with even the nastiest protections is, there's always someone who'll eventually either figure it out, or hack their way around it. The reason why it takes so long with some games is the amount of interest. The popular platforms come first.
Recently, a bunch of brainiacs has figured out the way to bypass Gaelco's suicide protection, which remained uncracked for ages. It took this long, because Gaelco's games aren't as popular as, say, CPS series of boards.
Plus, there's a difference between making something playable and actually cracking it. CPS2 was blown wide open only recently, with the ability to revive boards using genuine ROMs rather than phoenix ones. Banjo Tooie protection was finally cracked four years ago or so, while the game has been fully playable on emulators for ages.
