The extra short route to indefinite lifespan might be lab grown replacement organs. Some other stuff like brains'll prolly be a lot more difficult, but there's got to be some health benefits to complex stuff like brains, on top of extra lifespan, from having healthy "simple" organs for your whole life. After that you have to get into gritty stuff like extra and intra cellular junk, and of course cancer, etc. The important thing with living forever though, today, is that there doesn't need to be an immortality tech right away. You only need to survive long enough on less-than-perfect intermediate techs to eventually see the day some technology enables proper indefinite lifespan.
I don't know about brain uploading. There's just too much unknown at this point.. What if you very gradually replace your brain with synthetic stuff? In theory you can cram as much computational power as a whole brain into something the size of a grain of sand, if quantum computation works as it's supposed to.
The thing that I'm really curious to see with railguns is what these capabilities will do for major conflicts. Where with nukes you had such massive collateral damage and lasting scorched earth effects, with this one you've got dozens of megajoules focused in 15 feet error margin, and no current way to counter them. IOW you can rod the enemy with impunity.. That sounds like it could make blitz strategy more viable.. IOW the first one to fire could win an engagement. A country in a situation like North Korea's would probably love this kind of ability.
Could make for some cool war footage 30-50 years from now if lasers are the best countermeasure to railguns.