Mumble's and Gloria's son being named Erik can be seen as some rather clever foreshadowing. We know Erik will find his talent sometime in the film, but we're never really given much hint as to what that talent is. It turns out he's really good at singing opera like another famous Erik.
Erik's appearance also points to this. Whereas Mumble's bowtie mark and plumage looks like a tap dancer's tuxedo, Erik's bowtie mark and plumage makes it look more like he's wearing a cummerbund. Just like a male opera singer would.
It should be worth noting that Erik can't dance but he can sing, much like how his father could dance but couldn't sing.
