unless you are trying to get a magic key reservation (annual pass), the chances of not getting into the park because of no reservations available on a regular ticket (park hop or not) is pretty small to non-existent. And if you are staying at a Disneyland hotel, you are pretty much guaranteed entry.
I do think that, eventually, they will get rid of reservations for regular ticket guests, but keep it for magic key holders. As Disneyland is more of a locals park, with a lot of Magic Keys, it seems like they want to be able to control access, so I see no end date for removing reservations for magic keys.. No idea on when for regular tickets. Probably get rid of it first for hotel guests, to make it like a perk (not sure why they have not yet done so honestly).