This sounds like a great advancement, however an implementation in RDBMS products may be some way away yet - MSSQL uses 8KB pages by default, and I believe (without checking) that most other RDBMSes use at least 4KB. B+ tree index implementations on RDBMS products may be here to stay for a while yet unless these performance issues can be minimised, or unless there is a paradigm shift to use smaller pages - which would have a knock-on effect to query performance unrelated to indexes, such as number of page lookups, increased I/O for non-contiguous page reads...
I think an implementation in RDBMS is worth exploring. After all, the page size of the PGM-index can be tuned to match the one of the media you are storing your data to (or to match the default setting of the RDBMS).
About the paradigm shift to use smaller pages, it's worth mentioning technological innovations like the Intel's Optane DC Persistent Memory, in which the access granularity is 256 bytes. I expect that similar products will be available in the near future and that new/updated RDBMS implementations will take advantage of them.
