Segwit conservatively frees up 60% of block size.
Let say each trans is 250 byte with 1MB block
60% X 1MB = 0.6MB X 1024 X 1024 = 629,146 byte
629,146/250 = 2,517 transactions
2,517/600 = 4 TPS
we get 4 transactions more per second....I don't think that should be called scalability!