But Garner still feels Blackburn is an attractive prospect for Hughes' successor.
"If Rovers expand their net to get their man they may have to approach someone already under contract," said Garner.
"They may have to use some of the compensation money they have picked up for Mark Hughes from Manchester City to entice another manager out of his contract if he is already at a club."
He also feels the appointment is very important for the club's long-term future.
"Blackburn are in the same position as many clubs in the Premier League because they haven't got a lot of money to spend, and to follow Mark Hughes' prudent spending is a big ask. The board will be under big pressure to back whoever comes in," added Blackburn's all-time leading scorer.
"Do you go for an experienced man or do you take a chance with a lower league manager like Paul Ince? If you appoint Paul Ince he would need to bring in someone with experience at the same time to work alongside him.
"We've seen it time and time again when a big manager leaves a club that they seem to struggle the season after.
I wish whoever takes over the very best and good luck because believe me, following on from Mark Hughes is a big ask
"I really hope this doesn't happen to Blackburn. It's a massive job to take on, priority next season is firstly survival and I don't want to see the momentum built up over the past few years come to a grinding halt."
The prospect of a major player exodus is also a concern for the Boston-born Ewood Park legend.
"There's already talk of [David] Bentley and Roque Santa Cruz following him out of the club," said Garner.
"And Stephen Warnock also said he's not happy after signing a new four-year deal, that always happens when a manager leaves.
"I wish whoever takes over the very best and good luck because believe me, following on from Mark Hughes is a big ask."
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