West Brom have sacked Nicolas Anelka citing "gross misconduct" after the striker claimed on Twitter he had quit the club.
Mauricio Pochettino expects to be at Southampton next season and is looking forward to working with chairman Ralph Krueger.
Former Tottenham and Middlesbrough forward Mido, 29, has struggled for full fitness and has only made one appearance for the Tykes since arriving in the summer
Collins has not appeared for the first team at Barnsley this season following his arrival from Port Vale, initially on loan in March last year.
The 24-year-old, who started his career at Wolves, made over 130 appearances for Port Vale during a two-and-a-half year spell with the club before arriving at Oakwell.
He made seven first-team appearances last season.