After a close examination of the episode, I conclude is not possible to make any dogmatic conclusions that the allegedly altered timeline survived or existed.
And a quick glance at Memory Alpha doesn't seem to mention any "Hey did we sleep together?" follow-ups to the episode - but someone would have to read every novel.
EDIT: The Apocrypha section in Memory Alpha for TNG Tapestry does mention Q discussing the events of the episode later. (Obviously the novel Q-Squared, or any novel is not strict canon. It's just fun Beta canon you may enjoy for your personal canon.)
Honestly, I thought Marta and Corey were both dead the way Picard spoke in the past tense but they both lived on in Beta canon. Their deaths definitely would have made it impossible to prove in-universe. Marta and Corey being the only other witnesses to the events of Tapestry for Picard to compare events with (and Q).
Point of Logic 1: It is ambiguous whether the entire episode was a near death experience.
Point of Logic 2: Q could in theory do whatever he wants when he returns Picard to the moment just before the stabbing.
So that's two Bayesian strikes against the altered timeline.
Context
Once "play it safe" Picard avoids the fight with the Nausicaans he is instantly taken to the worst life imaginable - serving as a low level officer on his own ship the Enterprise.
When Q gives him the option to reset his fate back to the original - he is taken immediately back to the stabbing incident.
Given how identical the events are the viewer naturally assumes the altered events of the episode are still intact. BUT - we have not seen Picard's original past. We only see the stabbing on the heavenly "this was your life" replay. And so Q could have returned Picard to either version possibly.
Afterall this is an artificial timeline where Picard was going to end up in that confrontation no matter what because Q is controlling things. So much so I don't think that the similarity to the moment just prior to Picard going back to the future proves anything. Your opinion may vary - but that just establishes it's impossible to prove.
(Trivia: In heaven, if you watch closely you can see a Nausicaan lose his wig at the edge of the screen.)
So now there is no way to prove if there are three versions of the event or two. Specifically, 1. the original past with the stabbing, 2. the altered past with no fight, and 3. the altered past with the choice to fight to keep the timeline post-stabbing intact.
1 and 3 might be the same or different. And 2 and 3 might be a dream anyway.
Altered Past Version
NAUSICAAN: Coward. Like all Starfleet you talk >and you talk, but you have no guramba.
COREY: Why don't we find out.
PICARD: Don't be a fool, Corey. Look, there are plenty of other people to play dom-jot with. Now just go about your business.
Q Gives Picard the Choice to keep the Original Timeline Version
NAUSICAAN: Coward. Like all Starfleet. You talk and you talk but you have no guramba.
PICARD: What did you say?
NAUSICAAN: I said, you are a coward.
PICARD: That's what I thought you said.
Edit 2: I see in this question Picard's description of events in the original past is different.
Why are Captain Picard's Nausicaan recollections different?
PICARD: I stood toe-to-toe with the worst of the three (Nausicaans), and I told him what I thought of him, his pals, his planet, and I possibly made some passing reference to his questionable parentage..."
I suppose it is left to the viewer whether this happened in the past Picard returns to once he chooses to be stabbed. Again, I can't tell if timeline version 3 has version 1 or 2 in its past.
See Also:
Tapestry Transcript at
http://chakoteya.net/NextGen/241.htm
https://memory-alpha.fandom.com/wiki/Marta_Batanides
https://memory-alpha.fandom.com/wiki/Cortan_Zweller
https://memory-alpha.fandom.com/wiki/Tapestry_(episode)