The Hoops made the pledge when sounding out the Republic of Ireland assistant manager about the post.
Keane, who turned down the chance to take the position two years ago, has spoken of his enthusiasm to get back into club management.
But while his Celtic connections – he chose to finish his career at Celtic Park contributing to the League and League Cup double in 2005-06 – make him an obvious candidate, he is a famously tough negotiator.
Having witnessed the price Deila ultimately had to pay for failure in Europe, assurance on the amount of money available to strengthen for the bid to reach the Champions League group stages was high on Keane’s agenda.
That, though, was anticipated by owner, Dermot Desmond, and his Board, who are only too aware that serious investment on the playing side is necessary if the club are to once again be regular campaigners in Europe’s premier club competition.
A £15 million war chest certainly qualifies as that.
While qualification for the Champions League groups would bring in at least £20 million – and potentially even more – it can’t be guaranteed.
The potential risk, though, has been offset by positive financial developments which have made the increase possible.
Last week, Celtic announced the clinching of the biggest shirt sponsorship deal in Scottish football history, with the tie-up with betting firm, Dafabet, set to bring in £2.65 million per year for the next four years.
This followed on from the renewed sponsorship with Magners, whose logo will be on the back and shoulders, giving the Hoops two shirt sponsors.
However, it is Rangers’ promotion, expected to be worth up to a £10 million a year in additional revenue, that has given the Premiership champs most room for manoeuvre.
It remains to be seen whether the figure is enough of a carrot to sufficiently tempt the iconic former captain of Manchester United.
He has stated he is going nowhere until after assisting Martin O’Neill with the Republic of Ireland at the European Championships in France this summer.
What is certain is that Keane or no Keane, the size of the planned investment will give Celtic a much higher chance of landing a big-name replacement for Deila.
David Moyes, Brendan Rodgers and Paul Lambert are others on the club’s radar.