The point here is what is the GAF and possible partners after?
When the Typhoon was designed the GAF was after a fighter to replace their F4s and the RAF was after a light bomber to replace the Jaguar with it's, then, limited capability. Hence the initial limited GA capability.
Now, the GAF is after a Tornado replacement and wants an effective bomber/EW platform.
Two of it's Tornado partners, Italy and UK, have already made their choice - F-35, and don't need another platform in the same time frame.Most other nations need an F-16 platform and have/will go for either F-35 or Gripen. That effectively leaves France which will need to replace their Mirage 2000N/D in the same timeframe. So I'd turn my eyes to Dassault.
If the RAF need to fill the gap for a couple of years till Typhoon has a full capability, then the GR4 will just have to have another extension/LEP.
As to building a "new", Tornado, it's the same argument as a "new" F-18. The world has moved on, suppliers and technology are no longer available - and new choices are preferable.
If low-level isn't the preferred option, why carry around the weight and complexity of a swing-wing? It was the option for about 10 years, but with improved CFD other lighter designs work - so change the wing?
Then you change the engine, so that moves the CoG, and redesign the intakes to be a bit more stealthy. And with modern flight control computers you can make it more unstable and reduce the size/weight of the tail surfaces.
And when you've worked your way down a long list, you end up with 20-25% commonality, and a compromised design which... you realise is more expensive and less capable than starting with a clean sheet of paper. So you start over again.