Sure, if the 2020 codebase is ready.
this is not nearly as much about the code itself than about the process. bad process produces bad code, if you clean the code but continue with bad processes you are not going anywhere. with a good process even bad code is manageable. bugs in the game are the symptom but, ironically, are your last worry if you want to solve the problem, which is establishing proper process.
how much this takes is anybody's guess. frontier have given themselves 6 months and i'm very skeptical that's enough given my estimations (with no insider info) of what needs to change. it's a change that will involve moving people around first, not bugs: hire qa management and direction, educate staff, establish new routines, set up tools and environments to support them and automate test and build pipelines. in the end it means much less work and investment for better results, but it takes some prior effort to get there. it can potentially take years and one of the most crucial aspect is bringing high management to realize how important this actually is, and not sabotage their own shop mid way.