Greetings, and welcome to the CoE community. :)
Gentry packages (Bloodline, Settler, Propietor) won't play a role in the upcoming event Domain & Settlement Selection, only the nobility (Monarchs, Dukes/Duchesses, Counts/Countess) and the aristocracy (mayors) will be involved, but it doesn't stop one from later purchasing a title if they are interested in one.
You can purchase a lower tier pledge package and later upgrade it, you will just purchase the price between the packages when going to the next one.
At the end of the Domain & Settlement Selection begins April 29th, it talks a little about it:
What's Next
Once the main phase for Domain & Settlement Selection concludes on May 27, Elyria is so vast that there will definitely be properties still left unclaimed. As Caspian mentioned in the State of Elyria, there will be an opportunity for the untitled to snatch up unclaimed settlements or domains directly from the map! While the other benefits that came with the Nobility and Aristocracy Pledge Packages won't be included, such as Exposition Points or Design Experiences, the price will be discounted as a result. We expect this second phase of Domain & Settlement Selection will be every bit as exciting as the main phase promises to be! Look for details on phase two in the coming weeks.
Not all the information is hashed out yet, but one of the requirements for purchasing these titles after Domain Selection is having a Bloodline (or above) pledge package, and not owning an existing title. Pricing details and further information pending until it is ready then, though it will just be the title itself with no other game rewards attached to it (i.e sparks of life, pets, mounts, etc).
It was also discussed in the State of Elyria: The Calm Before the Storm update under "Domain & Settlement Selection for the Masses."