Why would I/we assume UT will rework subscription figures?

Not bad, but Unity will potentially be making a lot less money by unsuccessful games, compared to the past. Also, the royalty collection business is a headache for both UT and the developers.

How about this:

1) No royalties.

2) $50 - $60 for the initial subscription and $10 - $20 every subsequent month (all platforms). You are free to cancel any time, but when you resubscribe you have to pay that $50-$60 initial subscription all over again.

3) Ditch Unity FREE, it's ran its course. It just gives unity a bad name with its shortcomings, it really can't hold a candle to the low priced offerings.

4) Act fast to keep everyone on board. UE is still in beta and CRY engine has to put its money where its mouth is.

5) Give some generous asset store credit to users who preordered Unity 5 at the old price, keep your most loyal users happy.

 

That would be the best move for UT in my opinion.

Unity Pro is probably still a good deal on the long run for successful studios, but a lot of very small teams / new comers simply can't buy the Pro version and its addons.

And from my 3D guy point of view (I know it's a different story for programmers), UE4 is way too sexy in comparison.

Global illumination, post-process effect, PBR, the so convenient material editor ...
Gosh Unity free doesn't even allow me to use point/spot light realtime shadow.

These features for 20$ a month +5%, or even 10% on future gross sales ? I'd be totaly ok with that.

 

I think the 20$ a month will only work if you have a huge user base, something similar to Unity free user figures. I don't think there are enough Unity PRO users and uncertain if even Unreal Engine 4 can get that many users. Maybe they can, but changing your pricing like that is a huge risk.

 

With your suggestion, for 2 years of Unity Pro, UT will get $60 + 24*$20 = $540.
For 2 years of UE4, Epic will get 24*$19 = $456, plus 5% royalties from every game you make. (And you'll have to pay royalties for years and years).
Do you think 5% royalties really make up the $84 difference? No offence, but your suggestion is a joke.

What noisecrime suggested is the best option right now. That is if UT wants to deal with royalties after all.

 

I hope at least a good joke that made you laugh. However, I am sure anyone suggesting to Epic their current pricing two weeks ago, would have seemed at the time a much bigger jokester than myself now. You should not forget that although Unity Pro might have some edges over the competition, overall it does not compare favourably. This will only get worse as UE and CRY move to stable releases.
Thus, Unity has to be very aggressive in pricing to compete. Your $84 vs 5% royalties statement seems to suggest that Unity should aim to make as much money per user as UE does. This is not competitive or viable.

On the other hand what I suggested would lure many who dislike royalty based payments. It is cheap enough for all current users who have invested in Unity to stick with it, and it might compare favourably to some new customers, especially those doing 2d and smaller mobile games. It does not even begin to compete with Crytek's incoming offering, but lets see it materialize first. Now that $540 might seem tiny compared to what Unity was getting per Pro customer in the past, but hopefully the amount of paying customers will increase substantially and minimize the losses. Personally, I would be in for something like this (currently a Unity FREE user). For a 10% royalty, on the other hand... ehhhhh... maybe, but I would think it twice. $19 and 5% seems a better deal, after my current project would be completed, I would consider switching.

 

I think simpler is better, also if royalties are an issue(and I do see the downside to tracking them, probably even moreso for small crap) what about the model some companies use for indies where the indie license is a small amount but includes all features(one time fee per major version or a very small sub like $10/mo) and if you go above say $10,000(substance designer model here) you buy pro license for lets say $6000(more than current price to offset the indie licenses, I'm including all addons here as well).

No royalties in either case, and those that are doing this professionally can afford the extra 1k or whatever, the rest of the users get the full powered engine in hopes of becoming one of the pro users someday.