They will give you this discounted ticket if you show a US government military ID which can be a Common Access Card or a Active Military ID. Since you need one of the above to get on a base (like do), you can just buy them from the ticket office on a base.
Here's to the Heroes probably won't ever leave, it is extremely popular and imagine the complaints. I haven't heard of them discontinuing it, but they could be, they stopped themeing the bridge to the Heroes, which I partially like since it gives you a taste of their next biggest event a few weeks before.
However the main difference between an admission discount program and a roller coaster is, one has safety standards to keep operating that required heavy maintenance that was not worth keeping.
However, Here's to the Heroes has been around for what seems like ever and like Shafor mentioned they could be rebranding it. Perhaps they are going to change how they do military discounts/specials. Hopefully to include most government executive jobs, active or retired. To be honest, HTTH is very restrictive. A family of four gets 1 day each at one park each year, not including retired or police/fire/etc. Those two exceptions is what really upsets most people. So maybe they are going o change things up a bit for the better.