In an IT/system, there are cases where the latest technologies/solutions coexist with legacy sytems. The reasons to do so sometimes may be the budget limitation, lack of confidence in the new technologies/solutions. In such cases, old AND new system are deployed in parallel. However the ultimate goal is to modernize entirely. The process between the starting and end of this process could be called 段階的近代化 or 漸進的近代化.
Hey guys thanks for coming up with ideas..
In fact I had also thought of 漸進的現代化 or 近代化..
or 漸進的なリエンジニアリング or システム再構築..but the Japanese people I know said it sounds very literal translation.
Hurry San , the full sentence is "Progressive Modernization-The New Dimension"