I always believe that if human brain can think of it, it can very well make it possible. I mean who thought we will ever come up with something like virtual currency?
Do you think (even if hypothetically), a virtual world will give us a chance to introspect and find the missing links of the real world? By setting up the rules for the new world, will we realize what we did wrong with the real world?
It's not so much as "if you can think it you can make it possible" it's about execution. Immortality doesn't work like that, and it's not even remotely possible. It's not like mining a bitcoin, you're talking a life here. How do you think immortality will be achieved? Because there isn't a technology that can make this possible. Even with a super powerful computer, you still can't be sure it will make you immortal.