1. Given the risk, cost and limited upside, the onus is on the refactor team to prove that it needs to be done. Where is the ROI, factor in the risk. Where is this in the stack of things to do? Are there better ROI things?
2. Consider 'what the point' is in the first place, because the entire world could be run on python/SQL and it would be 'hard'. I don't think anyone would consider 'Mongo' to be 'hard' usually people use it because it's fast and easy, not hard. Consider maybe only replacing one part at a time, i.e. Java-SQL.
3. Consider a simple clean up or refactor. No need to learn no languages and tools when maybe you just need a house clean.
4. People seem to be going back to SQL because of it's inherent standardization - so many reporting and analysis systems use SQL as an interface, to the point where even NoSQLs are starting to use SQL.
I'm a big supporter of "replacing one part at a time", and wish I had done that on a rebuild I'm just completing.
In fact, I thought I was. We split our app into 3 parts, rebuilt part 1, then part 2, but part 1 couldn't be released to customers until part 2 was done, and we kept our legacy system supporting the majority of our users until we are done with part 3, which is nearing completion now.
I thought that was "replacing one piece at a time", but it isn't most users aren't touching it until part 3 is done, and at that point, they are experiencing a new system from scratch.
2. Consider 'what the point' is in the first place, because the entire world could be run on python/SQL and it would be 'hard'. I don't think anyone would consider 'Mongo' to be 'hard' usually people use it because it's fast and easy, not hard. Consider maybe only replacing one part at a time, i.e. Java-SQL.
3. Consider a simple clean up or refactor. No need to learn no languages and tools when maybe you just need a house clean.
4. People seem to be going back to SQL because of it's inherent standardization - so many reporting and analysis systems use SQL as an interface, to the point where even NoSQLs are starting to use SQL.