Red Bull tried to end its deal with Renault two years ago and in 2015 was turned down when it approached Mercedes about its class-leading power units.
Ricciardo, 28, will be a free agent at the end of this season when his Red Bull contract expires.
Aston Martin will not need to make a decision for a few months yet about its 2021 plans, but Palmer is clear that as long as there is a potential need for Red Bull to find an engine partner then it will keep its options open.
But perhaps Christian Horner put it best a yesterday's press conference, where, sitting alongside Cyril Abiteboul and Eric Boullier, when asked about Ricciardo, the Briton said: "Let's not forget that he has been in a vehicle that in the last couple of grands prix has been lapping the cars to our left".
"The first thing was to close the situation with the engine".
"Daniel understands the rationale, the engineering rationale, behind that".
"And frankly, in many respects, that is more important to us than the technical regulations, because that determines whether we have the financial resources to go into competition with the likes of Mercedes and the enormous amount of money that they have and can throw at this sport".
"Let's not forget that he has been in a auto that in the last couple of grands prix has been lapping the cars to our left [Renault]". So it would be a fairly bold decision to step out of a auto that he has won two grands prix in this year as a championship contender.
"We love Daniel, I've known him many, many years", said Boullier.
"I would be surprised if he was to leave the team because it's a good fit between himself and Red Bull but it's Formula One".
For those interested in their road cars and motorsport, Honda are big enough to buy Red Bull, which could be huge for the British firm should the relationship flourish. "At this time of the year it's still too early to talk about the line-up in the future, so it's just a normal, gentle discussion".
The Renault engine, while a victor twice already this season with Australian Daniel Ricciardo, is still down on power and unreliable - as is the Honda.
As Daniel Ricciardo ponders whether to remain at Red Bull or seek pastures new, there are numerous factors to consider.