How does Pine fit in with the other Jack Ryans? Alec Baldwin played the young Ryan in my favorite film of the series, 1990's The Hunt for Red October. When he fell out over the deal (in one of the great career miscalls in Hollywood history), Harrison Ford took over as an older Ryan in Patriot Games and Clear and Present Danger. Ben Affleck went younger again in 2002's The Sum of All Fears. What's great about Pine is that unlike many American male stars these days, he's masculine, athletic, dangerous--and a good actor to boot. He'll do fine.
At one point Paramount was developing an alternative Clancy series, starting with the 1993 novel Without Remorse, a Vietnam era thriller that doesn't feature Ryan (he makes a brief appearance, as does his father) but explores the character of the young John Clark/John Kelly played by Willem Dafoe in Clear and Present Danger. (Superman Returns star Brandon Routh was briefly mentioned for the CIA operative, while Clancy told Premiere in 2001 he preferred Matt Damon.) The studio announced John Singleton as director, but the movie never got anywhere. Another Clancy novel featuring Clark/Kelly, Rainbow Six, never got off the ground, even with Zack Snyder attached to write and direct.
Here's the Jack Ryan Special Edition DVD Collection.