Probability that Hillary Clinton will speak in primetime at the 2020 DNC?

[Mr. Morden]

What's the probability that she is offered, and accepts, a primetime speaking slot?

On the one hand, she's a high profile member of the party.  On the other hand, she's unpopular, more unpopular now than she was last year, and it's not clear to what extent that's going to change in the next three years.

And to what extent does it depend on who the presidential nominee is?  I'm assuming that she'd be more likely to speak at a convention nominating Kamala Harris than one nominating Bernie Sanders, for example.

[Mr. Morden]

If Hillary Clinton wants a spot she will have it.

The presumptive nominee pretty much has carte blanche to invite whoever they want to speak.  So if said person doesn't want HRC to speak, or at least not in primetime, they'll get their way.

[Mr. Morden]

It probably mostly depends on whether or not she wants a convention speaking role. Romney, McCain, W., etc. didn't speak at the 2016 GOP Convention not because they weren't invited to, but because they decided to not go. Usually, ex-nominees and ex-presidents are shoo-ins, with pretty much the sole exception of Richard Nixon.

Romney, the Bushes, etc. not speaking at the RNC in 2016 is an unusual circumstance: They refused to attend the convention because they didn't like the person being nominated: They wouldn't endorse Trump in the general election.  Barring some really unexpected scenario though, that won't apply to Clinton in 2020.  She'll (presumably) endorse the nominee.  If she skips out, it'll be more like Bush skipping the convention in 2012: Potentially a move to not create some kind of "controversy" over a polarizing figure appearing at the convention.  That assumes of course that her favorability #s will still be poor in 2020.  If her #s have recovered by then, then of course she'll speak in primetime.