Bitcoin is freedom. We run the network as a community so if every node shuts down it will be because the community has decided to shut it down, if not you can create your own node, I can as well and we build the network back up. As long as there are bitcoiners, there will be bitcoin.
Except you want to run a full node then downloading the whole Block shouldn't be your problem. You can run a pruned nodes to reduce the total storage which the block will occupy in your disk space, The current Blockchain size is around 651.13 GB [1] so it's even above your 500 GB space.
With a pruned node you will still need to sync your wallet with the blockchain requiring you to download every block to date, then prune the data. The problem here is internet speed and not space.