Don't get your hopes up, Fox isn't throwing $ at R rated "superhero" movies starring Ryan Reynolds anytime soon. You can thank Green Lantern & RIPD for that (not because they were rated R, cause they weren't, but if they had done well than the chances of Deadpool happening would be higher).
About the only way I see it happening is if they introduce him in another movie, or animate it.
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"The Rich are there to take all of the money & pay none of the taxes, the middle class is there to do all the work and pay all the taxes, and the poor are there to scare the crap out of the middle class." -George Carlin