A waste of time and money ?...Hardly, the technology developed for the Type 30 engines alone would be worth the program cost, fitting Mig-31BM's with a fully developed Type 30 engines as wells as the nose mounted X-band AESA, and the leading edge L-band AESA could increase the useful lifespan of those birds by additional 20 years if their airframes are kept in good shape.
The great question is :
Can Russia afford it ? In my view, Russia cannot afford it, neither US nowadays. You will developp a fighter, where only 30% of its fleet is ready in the best case, but in the reality around 10% are ready. F-22 is optimized only against poor third world countries, not against Russia, China or India.
Around 50 billions $ -it is not small amount of money, it is not nothing. - for the Pak T-50. Moreover, the AESA radar technology is not US origin, it is japanese origin. The PESA radar if I remember was soviet origin. Why must Russia follow US failling path ?
Thrust engine if I remember, Russia is still the leader, no use to mention air to air missiles, the final decisive moment in fight is still dogfight, regarding that Russia, is not the last.
Why will have Russia to follow the same F-22, and F-35's disastrous path ?