Lets try to think like the team in regard to your question:
Boom - Drafted 3rd round with what appears to have been the intention of him taking over for Whitworth at the end of his contract. His injury may have thrown a wrench in that plan, but now that Whit's contract I over we have to assume Boom would be starter.
Evans- Another 3rd round pick. The team had just lost Saffold and knew Blythe would be a free agent. Additionally, Blythe proved to be a weak link the in Super Bowl loss. We see with 'Boom that they expect 3rd round choices to become starters, so I'm going to guess that they picked Evans to start at one of the OG positions in 2020. Probably RG in this scenario.
Corbett- The team went looking for an OG, likely due to the underwhelming play of Noteboom and Blythe through week 6. Maybe they were just looking for depth, but it's been revealed that they had liked him when he came out. However, Allen's underwhelming play as a starter has got to have them looking at Corbett as an OC. Could he win the position, possibly.
Edwards - As a 5th round pick I don't think they were looking for a starter. His play was a welcome surprise. As things stand right now, he would probably be your starting LG.
Hav- As has been pointed out, last year was more the exception than the rule. He's under contract, so barring a trade for cap space, he's your starting RT.
Is it possible that this is next years starting lineup. Yeah, I think there is a pretty good chance of that with question marks only around the LG/OC combo.
