1) I'd like the IRS to at least have a role, since the IRS is the only one who has a copy of all my tax information provided by employers, banks, brokerages, etc. They have a unique role in that they can pre-fill all the information, where someone like Intuit cannot. However, an opportunity where they simply provided that information to a third party with my permission could also be an interesting model. I haven't seen any exploration of that.
2) California, at least, already provides this service. But few use it because the federal government doesn't. If the federal government stepped up, many states would follow.
I believe that the IRS providing it like most of the rest of the world would be a big step forward, but would be open to a role for private industry too.