I don't think that we should be counting on options 1 and 2. The reason is that with time, it won't make economic sense for people to store what they don't need for free. In 2020, it might seem like a cool idea for us fellow hobbyists to drop a few bucks on an extra 2TB disk just so we have a copy, but in 10-15 years, we might be filling up one of those 2TB disks (or even a 1PB disk) every few days. And while storage costs do drop with time, I don't think they'll drop off as fast as the rate of new transactions. Don't get me wrong, businesses who can make money might store things, but I don't think the cost will be as trivial as it is today. For now, if somebody is concerned that their data might be lost over time, I would encourage them to try and keep a copy for themself somewhere. Once it starts to make economic sense and once the demand emerges (i.e. once the cost becomes non-trivial for miners), I predict that we'll be able to pay a storage and archival service to keep records—but only the ones people care enough about to pay for, so probably not the entire blockchain after a certain point.
I don't think that we should be counting on options 1 and 2. The reason is that with time, it won't make economic sense for people to store what they don't need for free. In 2020, it might seem like a cool idea for us fellow hobbyists to drop a few bucks on an extra 2TB disk just so we have a copy, but in 10-15 years, we might be filling up one of those 2TB disks (or even a 1PB disk) every few days. And while storage costs do drop with time, I don't think they'll drop off as fast as the rate of new transactions. Don't get me wrong, businesses who can make money might store things, but I don't think the cost will be as trivial as it is today. For now, if somebody is concerned that their data might be lost over time, I would encourage them to try and keep a copy for themself somewhere. Once it starts to make economic sense and once the demand emerges (i.e. once the cost becomes non-trivial for miners), I predict that we'll be able to pay a storage and archival service to keep records—but only the ones people care enough about to pay for, so probably not the entire blockchain after a certain point.