I was determined to wait for the new model but now I have second thoughts.
It really depends on your finances and how significant that €1100 is to you. For many, that will make the difference between "can afford" and "can't afford".
The 2015 Mac is still a pretty good machine - the financial risk is that a few years in the future you'll need better graphics or need USB-C/TB3 connectivity and need to upgrade sooner than if you'd waited for the new model. So it might help to think about how long you'd expect the computer to last you & work out the "annual cost". E.g. if the new model costs €3000 and lasts you for 5 years that's €600/year, so the "bargain" would need to last 1890/600 = ~ a bit over 3 years to give the same value. Now, I'd feel pretty confident that USB-A will be around for 3 more years, I doubt apple will drop OS support that quickly, and at
worst you'll have to look on eBay for TB2 stuff, so that still sounds like a bargain.
(That's only a rough rule-of-thumb test, so don't over-think it)
You put your own price on the glow of having the latest and greatest...
Anyway, apart from that: in terms of general computing power, Skylake isn't dramatically better than the current rMBP CPUs and won't, in itself, make a big difference. The new Macs
should offer more of an improvement when it comes to graphics - which may include better support for 4k (or even 5k) displays as well as raw performance, but we don't have details yet and Apple aren't known for picking the most bleeding edge GPSs (and 4k/5k is possible with the current model). So - how demanding is your Photoshop/FCP use and would a modest increase in GPU power be important? The current model isn't going to break a sweat at your other applications.
Personally, I'd worry more about long-term connectivity - specifically USB-C and TB3. If Apple goes
all USB-C/TB3 then short-term it might be more of a hassle (and expenditure on adapters) than an advantage, but if you're looking a few years down the line then lack of (e.g.) USB 3.1 gen 2 might be an "ageing factor" on your investment.
Also depends on what you're upgrading
from - its certainly not worth upgrading stuff less than 3-4 years old to 2015.