I am just wondering, if it is feasible, preferably without huge learning curves, to get AI to sing a melody line using lyrics, within Dorico? It’s early days for AI, but there are a plethora of tools out there already.
You guys have probably considererd it?
Z
Cantai
Synthesizer V
There is a tool called Cantai that looks promising for “Classical” music that, if realized, will do just that!
Another tool, Synthesizer V, works very well right now, but doesn’t take the lyrics from the score, instead you have to type them into its UI. And it’s more catered to Pop, Rock, Jazz and Musical Theater styles.
Sythesiser V looks good, demos are japanese I think? Could be pricey especially with add ons. Also seems a lot of work for me, as I am presently a] learning Dorico, B creating a band, C picking up tenor sax again, d] learning a bit of congas, f] mowing grass, cleaning my car. 
I do remember looking into this question some years back and concluding the products was ready for prime time.
Cantai should be coming to Dorico soon. Some people like it, but the last time I listened to some output, I thought it was pretty poor.
If you export MIDI (Dorico 6), Synth V will import the lyrics. There will be some touch-up to do but much better than typing the whole thing.
Synth V is actually fantastic without spinning any knobs or tweaking any settings. You just need to learn how to input lyrics and every once in while you’ll need to tweak a phoneme. Additional voices are moderately priced (~ $75 USD, on average). It’s probably the best VST/App I purchased in quite some time.
You’re of course correct, I keep forgetting about this! 
Even cooler, if I may, is that SynthV can import a vocal performance, turn it into MIDI, transcribe the lyrics automatically and preserves most, if not all, of the original singer’s little inflections and idiosyncrasies. Then switch to a male voice e. g. and prepare to be blown away…
Yes, I forget whether this is due to the latest updates in Dorico or in Synth V, but I recall that direct import of MIDI containing lyrics is now possible where it was not always so.
Looks like Synth V is getting some traction here. Cantai is too Classical for my present needs. I shall remember this thread, but at the mo I am still Dorico-stupid. This is a medical term for a condition for which you can get special needs grants.
Any other AI also rans? Surely there must be more!
Z
Given the widespread needs of Dorico users, it is fortunate to have companies developing vocal synthesis that work with Dorico to provide either classical or more popular renditions.
This thread has some samples.
This is an old demo with V1 of SynthV without any tweaking, just the midi straight from Dorico and the lyrics typed into the app. 
I have been around Cubase for 30+years and have tons of apps, but this is very good. It it versatile though?
I just installed my copy of Synth V and I’m thrilled. Importing MIDI and lyrics from Dorico required some extra work, but you can simply specify Synth V as a MIDI instrument in Dorico, press Record in Synth V, and let Dorico play back the vocal part. Then all the notes are placed in the right place and with the right length in Synth V, and I can easily add the lyrics.
You can even render the whole thing directly from Dorico, using plugins in the Dorico mixer, etc. Fantastic!
Here’s an example video: –> Synth V singing example