I think that depends. Honestly I'd be surprised if it's as cut-and-dry as HT under no circumstances being allowed to do a character unless it's from SSC's past and in need of an update (as someone mentioned, SSC has never done a battle-damaged Bespin Luke).
SSC has to know that if they, for example, prevent HT from making a Leia so that they can do their own, then that Leia is going to be compared to HT's best work and if it's lacking in any way, they're going to be trashed and the figure probably will tank.
Really it'd be smarter for SSC (since honestly I can't see them competing with HT on the paint apps) to either let HT do the release of the human characters and take a cut, or work on the figure in concert, letting HT do the headscult/paint or learning from HT's production methods so that they can produce something of the same quality.
Basically, hoarding characters can cut both ways. It's great for SSC if they're able to match HT's quality but not so much if collectors find the sculpt and paint apps lacking.
First, LOL at the idea of Any Ot figures of the main cast Tanking.
SW has too many fans that will eat up complete crap with a spoon, just because it is OT SW, and then ask for seconds.
secondly, Have you seen the recent quality of 1/6th figures coming out of sideshow recently?
thirdly; HAVE YOU SEEN THE QUALITY OF 1/6TH FIGURES COMING OUT OF SIDESHOW LATELY?!
fourthly, Hot toys has said they will be doing a MAXIMUM of 1-2 figures a year, and have just hinted at the next three. Sideshow has PLENTY of time to release whatever they like, and get it out on the market. once sideshow sells a figure, if a better product comes along later on and destroys the aftermarket value, they don't care. If you think otherwise, you're fooling yourself.
Fithly, Hot toys is NOT Infallible. Have you seen their Flop of an indy?
Good figure or not, it's a flop As Indy, especially for it's price.
Also, hearkening back to my first point, people still bought it up, regardless of it being a flop. why? Harrison ford. Or his stunt double anyways.
Lastly, saying sideshow has never done a "battle damaged Bespin luke" is splitting hairs. They've done a Bespin luke. The EX version came with a hand stump, and his bacta turniquette. So if you REALLY wanna go that route, sideshow DID do a battle damaged Like.
It's worth mentioning that Hot toys is not doing a "battle damaged Luke" figure either. They're doing a Luke skywalker DX figure.