Oh sure, you can change ships if you want to!
It's very much like a vastly-upgraded version of Freelancer, or a single-player version of the popular "Eve Online" MMO. The simulated living economy in the X series is extremely robust and dynamic...it progresses with or without you.
You stand in one place and watch ships going to and from sectors, haggling and trying to make a name for themselves. It can be quite immersive.
I am so ridiculously hyped for this next iteration! Can't wait to play it.
No, you can't change ships. You can upgrade yours and buy others that are controlled by NPC's. It's not like Freelancer or EVE where you can physically pilot a bunch of ships.
Still excited to play it though.