The archaic-sounding verb methinks, meaning it seems to me, is likely to continue appearing in English as long as we keep reading Shakespeare, who, in Hamlet, immortalized the word with the line, “The lady doth protest too much, methinks.” Today, the word is often used in reference to the Shakespeare play, often with other language from that line—for example:
Angelo, methinks the coach doth protest too much. [Sports Illustrated]
It sounds reassuring, but methinks she doth protest too much. [San Francisco Chronicle]
Methinks Arsenal protesteth too much. [Telegraph]
But the word also appears on its own—for example:
Methinks it’s a bit early for superstar diva comparisons. [CNN]
I’d like to tell you sales of it go up when the moon is full, but methinks that would be a bit too much of a poetic fiction. [The Atlantic]
That will be Victoria’s hardest battle, methinks: to overturn her image of having more money than taste or talent. [Daily Mail]
In any case, the word always sounds like an archaic flourish, and it’s very difficult to use it in a nonhumorous way.