Nate Cohen, expert on polling and demographics:

The results suggest that Ms. Warren, who has emerged as a front-runner for the Democratic nomination, might face a number of obstacles in her pursuit of the presidency. The poll supports concerns among some Democrats that her ideology and gender — including the fraught question of “likability” — could hobble her candidacy among a crucial sliver of the electorate. And not only does she underperform her rivals, but the poll also suggests that the race could be close enough for the difference to be decisive. link

Warren will drop significantly more if nominated, from GOP attacks as a "tax raising big government elite east coast professor from Harvard", a "socialist", a "Maduro clone", "will turn America into Venezuela" etc. She has given the Republicans plenty of material to use against her in her 54 plans.  (yes, there are 54 of them) Even some of her single plans, like her 15,000+ word Medicare for All healthcare/tax plan make FDR's New Deal look like a business as usual continuing resolution. The Warren plan would kick 140 million or so off their current health care plans. Although some might not mind, millions who like their plans will mind. Many on Medicare may be concerned the system will go broke faster, leaving them at the end of the line.  Warren has no provision in the plan for anyone in the United States to pay anything per visit, which is an invitation to broken appointments and increased use of emergency rooms. There is no guarantee that doctors will not just opt out of the system and go full fee for service, causing further congestion at doctors still taking Medicare for All. It will overturn 18% of our economy and is sure to be a ripe target for all kinds of attacks from the Republicans and their PAC's.

She attacks her fellow Democratic candidates with:

"Serious candidates for president should speak plainly about these and set out their plans for cost control - especially those of us who are skeptical of Medicare for All"...every candidate who opposes my long-term goal of Medicare for All should put forward their own plan to make sure every single person in America can get high-quality health care and won't go broke - and fully explain how they intend to pay for it. Or, if they are unwilling to do that, concede that their half-measures will leave millions behind."

When she says "every single person in America can get high-quality health care and won't go broke", isn't that what Obamacare was designed to do? It mandates a limit on co-pays, no denial for pre-existing conditions, and no cutoff of insurance at a certain dollar amount. She in effect admits the every American is already getting high quality health care, as she should, for the quality of care is not determined in the Oval office but in the hospitals and doctor's offices of America. Obamacare insures no one on it will "go broke" due to health care expenses. Expand it, improve it, that may pass Congress.

Let's look at the Warren border plan. She calls it "A Fair and Welcoming Immigration System".  Much of the 3,100 word plan is about reversing policies of Donald Trump. Any Democrat if elected is going to reverse Trump's abuses at the border, and his cuts to legal immigration and his bans.  But Warren goes full open border. She has no mention of enforcement at the border, because her plan will decriminalize crossing it. If it is not a criminal offense to walk across the border, that is an open border. She does not mention the deportation of anyone.

Someone crossing will not be turned back or detained. If caught, they will let loose in the US after being given a distant court date, free lawyer and free health care. She does not mention deportation of felons, only mentioning "focusing on real threats". The only targets would be to "disrupt and prosecute human trafficking". Beyond that she also plans "amnesty" for 11 million or more "illegals" already here, and for any undocumented people who come here in the future and settle down. She calls it a "Fair and Welcoming Immigration System". In total, her plan would never pass Congress, and just serve as a huge target for GOP attack ads.

So the prospects are a Warren candidacy against Trump would end in an Electoral College defeat, perhaps even worse than Hillary. The "elite" Harvard professor would face a very uphill, almost certainly a losing battle, winning over the fence sitting, easily exploitable, low information voters in swing states as they are bombarded with preelection attack ads, funded by the huge cash hoard Trump and his allies are amassing.  They are the ones who will decide the Electoral College winner.