I think the coin value will be driven by the amount playbacks that take place.

i.e
Right now there are about 4 blocks solved per minute, * 314 coins/block that yields 1256 coins distributed every minute.
When UBI forks is activated, musicians will be paid a fixed income of $0.02 per play in $MUSIC. This $MUSIC will be coming from a shared pool, where of all coins mined, 20% go to this pool, the 80% remaining the miners keep it.

Let's work some numbers now.

As a reference, Spotify alone streams about 750K songs per minute. To keep calculations simple in this scenario, let's say there are 1256 songs played per minute in the Musicoin network.
1256 songs played means that there has to be 1256 songs * $0.02 = $25.12 paid to artists in $MUSIC during that minute. We know that this $25.12 is the 20% of some number (since this 20% comes from the UBI pool, and the remaining 80% the miners keep), doing the math this number is $125.6. Now we know that 1256 $MUSIC mined in 1 minute amount to $125.60, which gives a price of $0.10 per $MUSIC.

Scaling up the amount of songs played per minute is proportional to the price. Meaning, if instead of 1256 songs, now we have 12,560 songs played per minute, the price per coin would have to be $1, so that artist continue to receive their UBI of $0.02 per play.

Let's try that:
12,560 * $0.02 = $251.20. This comes from the UBI pool which is 20% of the coins mined so (x = 251.20*100/20) = $1,256.00.

$1256.00 per 1256 coins mined in that minute, so price per coin now is $1.

Did I just write a bunch of nonsense? I.. don't even know, y'all tell me. Meanwhile I'm gonna continue sipppin' this scotch.