WWE Superstar John Cena has sparked fears he could be set to retire from wrestling after posting a cryptic message on social media.With a post beginning, "all things end," the multi-time former world champion's tweet has seen the WWE Universe into meltdown with thousands of interactions within seconds.Cena, who last featured in WWE at WrestleMania 36 in a losing effort against The Fiend Bray Wyatt in the Firefly Fun House Match, said:All things end. When it’s time to leave, leave them guessing.— John Cena (@JohnCena) April 8, 2020While the 42-year-old stopped short of confirming that the message signaled the end of his in-ring career, speculation has been rife that John Cena might soon hang his boots.Cena has already spent the last few years working a vastly reduced schedule in WWE, while pursuing other opportunities outside of the squared circle.He's already fashioned a substantial career in film and television, but has never made a secret of the fact that WWE and its fans are where his heart remains.Cena is one of the company's most decorated performers. Since his debut on SmackDown in 2002 in a match against Kurt Angle, he's accumulated an astonishing combined 16 reigns as WWE and World Heavyweight Championship. He's also a two-time winner of the Royal Rumble match.