A lot of talk from warfare/strategy experts now that the battle for Kiev is essentially over and Ukraine has won it.
Lots more detail for the implications for that in this thread, especially around why they can't just regroup/resupply and try again, and what that means for Ukraine's negotiating position, and a quicker end to the war than some predicted (weeks and months rather than months and years).
My feeling is that there will probably be some kind of concession to Donbass/Luhansk independence, possibly via a referendum, constitutionally enshrined neutrality, so no NATO membership, though future EU membership will be on the table.
Russia has clearly lost any ability to either take Kiev and enforce regime change, or even cut Ukraine off from the sea by taking Odessa.
I think the question will end up being how humiliating the agreement ends up being for Russia, and the consequences for Putin's leadership. Giving Zelenskyy the power to agree and end to western sanctions could be the final nail in the coffin of Russia's ability to negotiate a favourable outcome for themselves.
I could be wrong obviously, especially if Putin decides to dig in in the East, arming and supporting separatist militias, with or without the direct support of the Russian military.
In that video of him being interviewed by Russian journalists, Zelenskyy himself mentioned a timeframe of about a year, taking into account holding a referendum (which refugee Ukrainians would be able to participate in) and also constitutional changes would require... I think it was two sessions of parliament or something like that.
He was a bit scathing of any seeming suggestions of him doing deals. He pointed out he's only the President and it would be for the people to decide and that any constitutional changes would have to go through parliament. So he's not turning into a dictator, not seizing total power, he's still respecting the political and legal processes.
In fact, one of the points Zelenskyy made was that Russia needs to bring some lawyers to the negotiations. (Because some of the things being suggested in negotiations are apparently not lawful for him to negotiate either way, or can't legally be done to a short timescale - iirc he can't just sign off on any nuclear and NATO stuff himself, some of the demands, he just doesn't have the constitutional authority to accede.)
And don't forget, although prior to being elected President he was an actor and comedian, he actually studied law, and he seems to have respect for law insofar as the extent of his powers go, and the political process, and the constitution. He's even got a lawyerly eye over the details. In that interview, there were questions and answers about a couple of allegedly faked documents purporting to be orders... iirc for Ukrainian forces to retake Crimea and Donbass (or something like that), Zelenskyy hadn't seen one document, but he had seen the other, which was purported to have been signed by him. He pointed out that it had been written in Ukrainian but signed VA Zelenskyy, for Volodymyr Alexandrovich when there's no 'A' in Ukrainian, in Ukrainian it would be written VO.
So someone like that is going to want to dot the Is and cross the Ts and the legal and political process is going to take however long it's going to take, which might be a considerable amount of time. There might be a ceasefire and tensions along the way, but I don't think he's going to take any shortcuts. He's fought this war for democracy and freedom and I don't think he's going to compromise those ideals in the negotiating process, I don't think it's in his nature to agree to do anything that would be unconstitutional, to overreach his authority as president. Although that might present difficulties when negotiating with an autocratic leader who's used to leading by strong arming and dictating.