Not in my lifetime . I'm 61 hell in nc we can't even hold office, it's in the state constitution. The white baby boomers in the south and midwest will have to pass.

I imagine Bernie Sanders would have been one to admit to agnosticism, though only after his term, which will maybe be how it first happens for whomever. I think it could happen in the next 20 to 30 years, given the changing poll numbers on the general population.

It will happen when we enter the age of Aquarius i.e. 2150. (yeah right, LOL!)

Does anyone here want to run on a secular platform?

OH NO! That would be the fall of an empire! Its aways been about power, control, and your money.
Hmmmm..... giving up being the Godfather...no way!

Yes, but it will likely be another 50 years or so. Right now the Christian right still has too much influence in politics for it to be acceptable to be an atheist in government (at least not in most areas). However the percentage of the demographics that are non religious are growing faster than ever before. The younger generations are also some of the most irreligious yet. Once the old theocrats die off, and the younger generations start to take center stage, you will start to see atheists take office.

Eventually, but no clue if we’ ever see it.

No.
Unless the Pres. can get the big money to follow them into office in the first place it won't happen.
At least not in my lifetime.
Our government is beyond corrupt and what better place to hide corruption than inside religion?

These days, I don’t think it would matter as much as most politicians seem to think. Bernie pretty clearly did not believe in a literal god, and if not for, as Noam Chomsky said, “shenanigans” by the DNC, he would be our president today. In the final analysis voters don’t really care about the religious belief of their politicians, as evidenced by the religious right installing an icon of materialism in the highest office.

Perhaps in the far away future. I have to believe that this current trend of people who profess to be Christians but are in truth haters will bring a split but not without struggle and viciousness. For a country founded on separation of church and state and religious freedom we are a mess. Change will come but not any time soon.

I think Bernie Sanders is an atheist, but he won't openingly admit it. It would be political suicide. He was definitely my choice for president.

eventually perhaps, but I would be surprised if it were any anytime soon.

Traditionally, the POTUS' religious affiliation is known, but not worn on their sleeve. Trump has (somewhat falsely, IMHO) used that X-tian label to leverage that vocal and active portion of the voter base very successfully. I don't think he's much of a X-tian. He just likes to give it lip service. To answer your question, I have no idea. I think that could come about someday when the majority of voters are non-believers and it is politically advantageous to be an Atheist, sadly.