(EDITED) Not a complaint, and certainly this not anything the Dorico team had anything to do with, and I suspect even @Steinberg had to follow the lead of their overlords on this.
Simply put, MakeMusic in 2025 concerning Finale end-of-life offered Steinberg a deal it could not refuse. Steinberg/Yamaha made the right choice, of course. Imagine Avid getting ‘hold of Finale - horrors!! (UPDATE: Thanks, @Cookie_Jarvis: As it turned out, no offers were make or whatever. I think there was a legal agreement of some sort? Maybe not.)
When Adobe Flash reached end-of-life, Adobe killed it the right way: end-of-life in 2020 was announced in 2017, giving developers three years to port their work or somehow free their work from Flash.
Software eventually becomes so antiquated, its code can no longer be feasibly reconciled to a modern digital environment. This seems to have happened to Finale, and it will happen to even the mighty Photoshop. (Three decades ago, Adobe PageMaker was superceded by InDesign.)
Ergo, when MakeMusic announced Finale was too long-in-the-tooth for future development, I believed it and still do.
What upsets me still over the whole thing was that MakeMusic did not give the grace-of-time Adobe gave its Flash-users. Even the span of just one year would have been far-better than the nerf-bat it gave the Finale community, shutting Finale from new users and even new downloads from already-existing users (from which MakeMusic had to do a U-turn).
A minimum time-span in advance of end-of-life of three years would have sufficed. I would have put on a minimum of seven to allow users living in a cave to find out about Finale end-of-life and to at least export their work to .xml while making .pdfs of all their work.
The fact MakeMusic did no such thing tells me the decision to kill Finale in such a brutal manner was made by a twenty-something hotshot using Excel.
Were it for me to have done, I would have in 2025 fixed Finale’s bugs as best as possible, maybe put in one last new-feature update fixing little things here and there, and then suspend further iteration on Finale forever except for OS compatibility, bugs, and security updates, keeping this status quo for seven years from an announcement made about three months later, but letting it leak that an announcement was imminent.
During the seven-year time-period, new users would be welcomed with the proviso Finale would be priced at the same rate(s) as Dorico going forward during the seven years, yet there would be no future feature-updates, though bugs, security, and OS compatibility would be addressed.
When the seven years was done, that would be it. Finale would continue to be downloaded for existing users, but no longer available for new users. The final version of Finale would be future-proofed enough to where the next few Windows and MacOS iterations could possibly run it.
Of course, at the start of the seven years, an arrangement with Steinberg would go into effect. Moreover (and MakeMusic may have already done this), a consortium would be set up between the major music-notation outfits (including MuseScore) who would together work on XML/Music XML and SMUFL, making both continually available to all, inside and outside of the consortium.
As it stands, Yamaha has done a very good thing in allowing Steinberg and MakeMusic to come up with the situation we actually have. Had Finale been (God forbid) made open-source, the commercial music-notation industry might have been destroyed.
And I’m glad the open-source MuseScore exists and (at least appears to be) doing well. Its very existence keeps Yamaha and Avid awake at night and the future of music-notation more competitive and iterative, adapting to user-needs for years to come.