The 61-year-old has contacts in Spain after moving to the country following his exploits for Northern Ireland there in the 1982 World Cup.
Armstrong spent two years at Real Mallorca, and clearly has either an informed or well educated opinion about what could happen to the goalkeeping situation at the three clubs.
“Well for a start David De Gea is definitely going to Real Madrid," he said on Kicca. "That is a certainty. And that will leave a big gap at Manchester United which is almost definitely going to be filled by Tottenham's Hugo Lloris."
Using words like 'certainly' and 'definitely' are big claims by the former forward, though many, including the likes of the Star, think the two deals are a distinct possibility.
But it is Armstrong's words about who Spurs might line up to replace the Frenchman that are surprising, with him mentioning the departing Real Madrid and Spanish icon Iker Casillas as the perfect fit, and more relevantly, a willing one.
“That leaves Tottenham without a first choice keeper which brings us back to Real Madrid and the legend that is Iker Casillas," Armstrong continued.
“Reports suggest that Iker does not fancy a move to Turkey and a move to London is an attractive proposal
“Casillas would be great for Tottenham. He is obviously hugely experienced and still very ambitious.”
Despite Casillas's age, signing the World Cup winner would be some coup for Tottenham. Interestingly, all three possible deals are driven by interest in De Gea by Real. It isn't a stretch to suggest that neither the Spaniard or Lloris would be pushing for moves if there wasn't pressure from the La Liga giants, while both Spurs and United would surely rather keep hold of their goalkeepers.
So with the summer of high profile goalkeeper switches yet to really kick off, there's a chance three clubs involved may just play a game of musical chairs between the goalposts.