Yep! This should make it super easy, there are no code changes needed so you can go back and forth between Lambda and traditional hosts as often as you please.

Yep! This should make it super easy, there are no code changes needed so you can go back and forth between Lambda and traditional hosts as often as you please. No "lock in" - although one of Lambda's advantages is how well it ties into the rest of the AWS ecosystem with RDS/S3/CloudFront/etc.