Hmm, I don't think saying ASL might become outdated is akin to saying speech may become outdated. Speech is the easiest form of face to face communication -- ASL is a convenient form, but I don't think it's clearly the easiest. I think that as technology continues to get cheaper, it is entirely possible that more people would have access to a talking keyboard. There have also been advances in brain-to-computer communication that might mean sensors could do the job when the person thinks, instead of them having to type.

I doubt ASL will be irrelevant in our lifetime, but I think it will be irrelevant long before humans stop verbally communicating.