Sadly, almost cruelly, it's hard to know which of the reported angles is worse for the once-revered Spaniard.
According to Marca, Los Blancos are closing in on a €10 million deal for Levante's Keylor Navas on a possible five-year contract, a move that would shift Casillas to third in line for the club's goalkeeping position, were the Spain captain and Diego Lopez to remain in Madrid.
If murmurings from AS (h/t Football Espana) are to be believed, Casillas has a pact with Real Madrid president Florentino Perez that will allow him to leave on a free transfer in 2015.
Conversely, El Confidencial report (as relayed by Jamie Bowman of the Mirror) that the declining keeper is desperate to leave the Spanish capital and head to London to join Arsenal—a club looking to add experience and competition to the squad's goalkeeping stocks to fast-track the development of Wojciech Szczesny.
Is this really what it has come to for a player who was once considered to be among the finest exponents of his art? Relegated to third place in his club's pecking order? Set for the ignominy of a free transfer? Ready to act as back-up to a 24-year-old? All while he's in—theoretically, at least—the prime years of a keeper's career in his early 30s?
Professional sport can be ruthless. Even to those who have reigned supreme.
Of course, understanding the rapidly approaching ending to his Real Madrid career is extremely straightforward.
Following two consecutive seasons of playing second-fiddle to Lopez at the Bernabeu, "San Iker" had his lingering deficiencies alarmingly exposed at this summer's World Cup in Brazil.
Having watched three already smashed past him, Casillas' gift to Robin van Persie for Netherlands' fourth goal in a 5-1 rout encapsulated the feeling of utter capitulation surrounding Spain's campaign in South America.
Just a handful of days later, with his confidence shattered, the Spanish captain pulled the curtains down himself on La Roja's World Cup defence, punching a free-kick to the feet of Charles Aranguiz to allow Jorge Sampaoli's Chileans a decisive second goal.
And those glaring mistakes had come on the back of his blunder that almost cost Los Blancos their 10th European title in the Champions League final against Atletico Madrid in May.
What Jose Mourinho had first acknowledged 18 months earlier also became evident to Carlo Ancelotti, seeing Casillas pushed into a secondary role. Only Vicente del Bosque preferred to buck the trend and maintain his faith in the Spanish icon.
La Roja's boss will be forced to follow suit now.
In the search for consolation, Casillas can take heart from the fact that he's not alone in his situation.
East of Madrid in Barcelona, the keeper's long-time friend and Spain teammate, Xavi, is facing an equally lamentable conclusion to his career at his own boyhood club.
Also recognised among the finest talents of his generation, the once-unrivalled playmaker could be set for a move Stateside to possibly join New York City.
Possessing a rare bond for two men from their respective cities, Casillas and Xavi are watching their careers mirror one another, sadly watching their supremacy fade after leading both their clubs and their nation to the pinnacle of the game.
Curiously, it was only four years ago that Casillas stood as the pre-eminent goalkeeper in the sport.
Dubbed the "saviour of Spanish football," by ESPN FC's Graham Hunter, the supreme shot-stopper had played a leading role in guiding Spain to the capture of the nation's greatest triumph—the 2010 World Cup.
While Cesc Fabregas' penalty against Italy in the quarter-finals of Euro 2008 has been recognised as a turning point for La Roja, Casillas' dramatic one-on-one save against Arjen Robben in the World Cup final two years later stands as perhaps the nation's most decisive footballing moment—an act that precluded Andres Iniesta's winner.
That peak feels incredibly distant now.
Suddenly, the aura that once surrounded Casillas has dissolved. The qualities that saw him idolised in Madrid and across Spain appear to have been vanquished.
Los Blancos fans will remember the precocious talent who lifted a Champions League trophy at just 19 years of age, capturing the imagination of Madridistas for a decade thereafter with his bold and extravagant style, sparkling reflexes and authoritative presence—all at the back of club football's most famous team.
"He's a phenomenon," Luis Aragones once said.
Sadly, that phenomenon is approaching a rather undignified exit from the very goal he once made his own.