Suppose Hubble needed to be fixed by replacing an accessible module again and NASA called for help, what are the most likely mission proposals?

Question

Background

Hubble has had at least a few troubling issues that were resolved from the ground in recent years, a summary can be found in Engadget's NASA struggles to fix a Hubble Space Telescope computer glitch

Beginning of question post

There have been several Shuttle missions to Hubble; the first to deploy it, one to fix the optics so it could actually work, others to upgrade, there's a list here: Shuttle Payloads and Related Information - Hubble Space Telescope and Great Observatory Missions

• STS-31 Discovery, April 24 - 29, 1990. The Hubble Space Telescope was deployed to a 380-statute-mile orbit.
• STS-37 Atlantis, April 5 - 11, 1991. The second great observatory, Gamma Ray Observatory (GRO) was deployed. This observatory has since been renamed the Compton Gamma Ray Observatory in honor of Arthur Holly Compton.
• STS-61 Endeavour, Dec. 2 - 13, 1993. The first mission to service and repair the Hubble telescope.
• STS-82 Discovery, Feb. 11 - 21, 1997. The second mission to service and repair the telescope.
• STS-93 Columbia, July 23 - 27, 1999. The third great observatory, Chandra X-ray Observatory was deployed.
• STS-103 Discovery, Dec. 19 - 27, 1999. The third mission to service and repair the Hubble telescope.
• STS-109 Columbia, March 1 - 12, 2002. The fourth mission to service and repair the telescope.
• STS-125 Atlantis, May 11 - 24, 2009. The fifth and final mission to service and repair the telescope.

Question: Suppose Hubble needed to be fixed by replacing an accessible module again and NASA called for help, what are the most likely mission proposals?

Is there some space robot under development or at least on a "credible drawing board" that could unscrew and pull out a module on the Hubble and slide in a new one? If Hubble was healthy except for one module and in need of this in order to start doing science again? If NASA or some agency put out a call for proposals to attempt a robotic module replacement, who might the most likely and credible bidders be?

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Related:

• Besides HST, JWST and stations, are there any examples of satellites designed for service in space? note: @Hobbes' answer says "NASA does not consider JWST to be serviceable"
• Is Landsat-7's propellant resupply port "robot-ready"? (Restore-L mission)
• Why Was DARPA's Orbital Express Refueling Program Discontinued?
• The JWST - What happens if/when it breaks?
• What satellites did the Shuttle retrieve from orbit?
• Why Was DARPA's Orbital Express Refueling Program Discontinued?
• What happens to JWST after it runs out of propellant?
• Satellite retrieval, fix and deploy possible remotely?
• Why Orion can't be used to service JWST?
• Is it possible to refuel the James Webb Space Telescope?
• With an external airlock attached, could Commercial Crew Program spacecraft service Hubble?

On the outreach page (of Restore-L) there is a NASA video Virtual Tours of NASA Goddard's Satellite Servicing Capabilities Office, and an animation there caught my eye. Here is a GIF reconstructed from frames of the video:

Answer 1

NASA Pretty much accepted that when the Space Shuttle was retired that there would be no more servicing missions to the Hubble. As above in the comments James Webb is the replacement for Hubble.

That being said NASA is apparently still looking to boost the orbit (do the study yourself, no promises): https://spacenews.com/nasa-request-information-on-hubble-reboost-options/

Or even looking for a Space-X mission: https://spacenews.com/nasa-and-spacex-to-study-possible-private-hubble-servicing-mission/

I would be surprised though if they actually do come through on a servicing mission.