They can’t bring them back simply because the two camps has Manpads, so even if you warn both Ukraine and Russia in advance there’s still a high risk of being shot down.
I don’t think the TFX will come around 2050, but more between 2030 and 2035. The first block of the aircraft will use F110 engines, and they’ve already been delivered according to TAI, so no problem regarding the engines.
The TPE331-10 used on the MQ-9 has a power output of 940 hp, 200 more hp compared to a single PT6A-135A engine used on the Akinci B. So totally doable.
Well with 2x750 hp engines it will surely have the ability to carry quite a bit of payload. The Kizilelma with the future TF-6000 engine would probably fly above 50.000 feet at least.