This is an interesting concept and similar to some of my ideas.
SAF would definitely have greater range than hydrogen, so how the “dual fuel” concept is implemented would relate to aircraft range.
This design looks similar to the NASA X-66 Sustainable Experimental Airliner which would extend the range due to better aerodynamic efficiencies.
https://www.nasa.gov/image-article/new-look-at-nasa-boeing-sustainable-experimental-airliner/

Using the NASA design combined with the MTU Water Enhanced Turbines (WET) would lead to an even greater range, much more than their “ flight range of 2,590 km (1,400 nm).” The SAF and/or Jet fuel tanks could be in their typical location of the wings, so this concept might be able to switch between the fuels easily. Maybe explore the use of using partial combustion using both fuels which would also extend range.

My final idea would be to explore Liquid Organic Hydrogen Storage (LOHC), which has almost the same volumetric energy density of liquid Hydrogen (Liquid H2 ~60kg/m3 and LOHC 54 kg/m3). It would be necessary to handle the endothermic dehydrogenation of LOHC (around 300 degrees C) which would require something like the MTU Water Enhanced Turbine.
LOHC has similar handling characteristics to jet fuel, so the LOHC could be placed in regular belly tanks with the SAF/jet fuel in the wing tanks. This would mean almost no loss of range for the aircraft.

References:
http://evs36.com/wp-content/uploads/finalpapers/FinalPaper_Acher_Thomas_Will_Christian.pdf
https://about.bnef.com/blog/liebreich-the-unbearable-lightness-of-hydrogen/
https://greengroup.mit.edu/lohc-powertrains-decarbonize-long-haul-trucks

The one of the two LH2 tanks in the rear could be moved to the nose of the aircraft, thereby achieving good weight balance at all phases of flight. This will also save weight, because this will shorten the tail section and hence lower the bending load on the tail end of the fuselage. The cockpit is simply placed behind the nose fuel tank, and the pilot can view outside via multiple cameras instead of a glass windscreen like in normal aircraft.

An aircraft optimized for LH2 would have much lower gross weight for the same payload capacity due to reduction in the size and weights of the wings, tail, engines, and landing gears..., though the wings still can hold regular kerosene jet fuel, but because the wings are smaller, will carry less jet fuel and thus will have lower range when using jet fuel.

@Gryf,
LOHC would be far too heavy and will never have any role in aviation. Nothing can beat LH2 as aviation fuel, due to the incredible lightness of LH2 that can nearly DOUBLE the payload-mile fuel economy per BTU of fuel energy. So, with LH2, the airlines will use 1/2 as much fuel energy per flight, and this will permit LH2 prices to cost twice as much as jet fuel per BTU of energy to come out even. If LH2 will ever cost the same as jet fuel per BTU of energy, then all airliners will be fueled with LH2. Fuel cost is the biggest operating expense for airlines.

More lame Greenwashing.

@Roger Pham
Stop using Gravimetric measures, i.e kWh/kg. Using kWh/liter is the correct measure and LOHC and LH2 are very close.

So what is your background?

In aviation weight is an important factor this is why LH2 is of Interest it takes up more space but it weighs less let's not get hung up on people's backgrounds mine's bigger than yours that is childish.

Gryf:

Your comment was a bit: ' A cat shouldn't look at a king'
Arguments of authority are not persuasive.

Now I have no technical background whatsoever, but am not too bad at adding up, and my understanding is that fuel weight is pretty critical in aviation, and LOHC looks pretty darn heavy.

Sure, you can do it, but you spend rather too much energy lugging the fuel around instead of payload, in a negative spiral.

For that reason it appears clear that the range of a aircraft running on LOHC would be less than the same aircraft fuelled by jet fuel.

Perhaps it is reasonable to assume that Fokker are not considering LOHC but SAF or hydrogen for that reason,

If that is not the case, please explain why.
Expertise is all very well, but if you put two experts together on many subjects you will get three opinions, so 'because I say so' is neither persuasive not informative,

Just had another dig around the influence of weight on fuel consumption in aircraft, especially for relatively short haul single isle, which is what is under discussion, ie broadly in the 737 class for a couple of hours or so flights.

https://www.pprune.org/tech-log/9473-how-much-extra-fuel-carry-fuel.html

'Orangewings' comment is the pertinent one:

' On the B737-300/700,for every tonne of fuel above flight plan fuel carried,we burn an extra 40kgs. So for 3 extra tonnes on a 2hr flight we burn an extra 240kgs.I think.'

Note that this is for a marginal increase in weight.
Obviously weight is the relevant metric, not volume, as the size of the fuel tanks are fixed, it is just how much they are filled, ie the weight of the fuel.

For LOHC or ammonia, which one commentator suggested, you are not talking about a marginal increase in weight over jet fuel, but multiplying it by several times.

That is clearly a complete non starter, which is why it is not contemplated by the very expert folk at Fokker and Airbus, who are looking to SAF or hydrogen.

SAF is identical for weight and volume with jet fuel, which is why it is the easier fix.
Hydrogen is more bulky although potentially weighing a lot less, with composite tanks, so really needs redesigned aircraft as well as low temperature hassles,