I really don't think attractions from neighboring parks plays any role in the future strategy of SFSTL (as mentioned Boomerang, Pandenomium). Plus, it is clear that SF is trying to capitalize (squeeze every drop of life) on their current attractions either by relocation or redesigning and improvement . So breathing new life into Park's Signature coaster via Iron Horse has better chance of happening than getting something new.
...Plus, if done right, the Boss would be 10x's better than it is now and we can finally get rid of those 'G' trains.