Is it worth waiting for the 10.2 release before creating new relational databases? What impact does the new relational model have on existing relational databases using the lookup( functions?
A proper beta will take a longer time to simmer or work through than most would expect. As 10.2 is in beta, if you have a need today, build your database today.
10.2 will not have any impact on your lookup functions. 10.2 will have some fantastic features that will make it easier to manage relations. Do recognize that many who use lookup functions today may or may not choose to later re-write those sections of their code to take advantage of new tools. Some believe in the process of 'If it works, don’t fix it."
I was wondering if the update would automatically convert the relational elements to the new feature or if you would end up with new and legacy databases.
No, the update does not modify your existing databases; all your lookup functions remain unchanged and working. You just get a new set of tools that make the work easier and faster.