The Administrator Client has not used Ecipse functionality and so has had minimal enhancement since R7. With ICAA, it's not possible to have the Administrator client running at the same time - you get a message "IBM Client Application Access is running. Please close to launch IBM Notes". It's unclear whether the same will also be the case for HCL Places.
If so, this means Domino administrators - one of the key personnel for supporting end users - won't be able to support users of ICAA and potentially HCL Places.
To allow administrators to effectively support their users, at the very least the current Administrator Client needs to run standalone. This may work within HCL Places (full client is Windows only, so possibly not), but alternatives could be making it standalone or running as a Docker container (Docker runs on Windows PC).
A better option may be making all current functions API-driven, with the relevant security. Considering that many administration functions may be relevant for JavaScript developers, e.g. in a DominoAdmin npm module, there may be a degree of development of APIs. Most are presumably available at C++ layer, at least for Windows. If completed across the board, this would enable a PWA or other modern client to be built.
Agreed. The existing Web Administrator could even be updated to run on the latest browsers and provide all the same functionality as the Notes Administrator - and not be Java dependent e.g. for the live console.
In theory if all Domino task support API then you could build an application to replace Domino Administrator. Not sure how long this would take though.