The S-37 is just the Russian counterpart of the X-29. It's a research airplane. There's no indication it or it's features will be designed into a production fighter. Impressive in size & presence though. The similarities between that and the X-29 program are interesting. Obviously, the S-37 has some heritage with the Su-27. The verticals look like a straight carryover, and the fuselage looks pretty common too. The X-29 borrowed parts from existing designs as well. The forward fuselage section is literally an F-5 fighter. The landing gear is F-16.