Can the base X1 be upgraded through components to any of the other two superior models?
TL;DRThe base X1 can't be fully upgraded into the other variants because of structural differences, though component swaps can approximate them, with the result heavier and less capable than the dedicated variants.
As mentioned above: not completely due to them being actual variants with fundamental structural differences. You could remove the weapon and swap the internal components out to configure a base X1 similarly to a Velocity but it won't be as light or nimble as the dedicated variant. Additionally, you could swap the Laser Cannon for the Laser Repeater (or other weapon of choice) and upgrade the internal components to Industrial components like the Force variant, but there still wouldn't be a structural hardpoint for the second shield generator, so you'd end up with a heavier X1 Baseline. Often, variants represent a design tradeoff where we push a given design to perform even better at certain edges of the envelope, and that makes them special - but we expect overall customization to be part of the fun also, and look forward to the type of X1 you can make for yourself.