From experience the kisses of death for folk clubs seem to be:

(1) Lack of supportive venues (i.e. clubs having to move at the whim of a brewery/change of management, and loud music in another bar drowning out the music in the club).
(2) Regulars becoming too introspective making 'outsiders' feel unwelcome.
(3) Lack of professionalism in club organisation, e.g. starting late.
(4) In-fighting between those who want to stamp their authority on club policies and those who pull there finger out and actually do the work.