If Boeing built a 49m single aisle, an increase of roughly 15% seating over the A321, and added a 42m CFRP wing, could the GTF get that aircraft to 3,000 nm range? If a majority of flight are 2 to 4 hrs, why worry about mid-market range? Go for mid-market capacity if 35K engines will perform that task.
Many people have done analysis on a theoretical A322. Using the 101t MTOW of the XLR and a simple stretch to 50m the range of the A322 would still be well over 3,000nm. I remember seeing a few respected members mention it could fly as far as 3,500nm. This is a 1,200nm or 25% range reduction over the A321XLR. The 787-10 for comparison is also a simple stretch and it loses only 15% of its range compared to the 787-9.
So a 49m long Boeing cleansheet with code D carbon wing would probably fly more than 4,000nm with the current GTF engines.
If 3,000nm was as far as you wanted to go then this theoretical aircraft could be 757-300 length and still use the same A321NEO engines. The 757-300 can fly 3,400nm but with a MTOW 8t higher than the 757-200. On the ACAP document at 113t takeoff weight the 757-300 can fly the brochure payload 2,500nm. The latest Pratt GTF should extend that to your 3,000nm target. I am sure the 757-300 would operate fine with lowered powered A321NEO engines providing the takeoff weight was kept around 110t.
The 757-300 with PW2040 engines requires a 9,900ft runway at the 123t MTOW. At a 115t takeoff weight the runway required drops to only 7,200ft. At 110t it requires only 6,700ft. With the lower powered A321NEO I am sure the runway would stay around 10,000ft. It would probably still have better runway performance than a 737-900ER.