Terminal, Cambridge English Dictionary
(of a disease or illness) leading to death:
His mother has a terminal illness.
By extension, one can use terminal as the OP did, to describe the condition of a company or an institution that cannot survive. Oxford English Dictionary:
c. fig. and in extended use: irreversible, irreparable; extremely
severe; calamitous, disastrous.....
1981 Daily Tel. 21 Dec. 2/1 Another contest for Labour's deputy
leadership next year could prove ‘terminal’ for the party, Mr Neil
1996 Big Issue 15 July 12/1 The business went into what many
thought was terminal decline.
And, in case a reader cannot access the OED, see this definition from Oxford Dictionaries
2.3 informal [--] Extreme and usually beyond cure or alteration (used for emphasis)
‘an industry in terminal decline’
‘you're making a terminal ass of yourself’