What has substantially changed in the warring sides' positions that now makes peace possible?

First, here is The Wall Street Journal clarifying what Putin wants, which hasn't changed:

Russian President Vladimir Putin presented the Trump administration this week with a sweeping proposal for a cease-fire in Ukraine, demanding major territorial concessions by Kyiv—and a push for global recognition of its claims—in exchange for a halt to the fighting, according to European and Ukrainian officials.

...European and Ukrainian officials, who were briefed by Trump and Witkoff in a series of calls this week, said they worry Putin is simply using the offer as a ploy to avoid new U.S. sanctions and tariffs while continuing the war.

Next, here's The New York Times presenting President Zelensky's Saturday firm rejection of giving up any land - and not even offering Crimea which has been fully controlled by Russia for many years, having been formally annexed in 2014 via a popular referendum:

President Volodymyr Zelensky of Ukraine on Saturday flatly rejected the idea that Ukraine could cede land to Russia after President Trump suggested that a peace deal between Ukraine and Russia could include "some swapping of territories."

"Ukrainians will not gift their land to the occupier," Mr. Zelensky said in a video address from his office in Kyiv, several hours after Mr. Trump's remarks, which appeared to overlook Ukraine's role in the negotiations.

...His blunt rejection risks angering Mr. Trump, who has made a peace deal between Ukraine and Russia one of his signature foreign policy goals, even if it means accepting terms that are unfavorable to Kyiv. In the past, Mr. Trump has criticized Ukraine for clinging to what he suggested were stubborn cease-fire demands and for being "not ready for peace."

Zelensky had further said in his video address, "Any decisions made against us, any decisions made without Ukraine, are at the same time decisions against peace." He then clarified Ukriane's position further, "They will bring nothing. These are dead decisions; they will never work."

If this is indeed the case, now what? What will Alaska achieve? Interestingly the Europeans have also been asking for a seat at the table regarding any Washington-Moscow talks to end the war.

If Trump wants to see this through, he'll have to cut of Zelensky - both in terms of arms supplies and pushing him out into the politicla cold, or isolation. But the European allies will of course revolt, and accuse Trump of being steamrolled by Putin's demands.