To be clear, this is not a request to upgrade a game to include a 'Deluxe Edition' DLC or something similar, that already exists. This is a request to have a feature to know when your game has been superseded by an entirely new entry such as a remaster, and a pathway to obtain.

I've noticed of late that many of my games have been replaced by newer versions of the same game such as a Remaster.

Some developers offer these new versions for free, some do not, that is there prerogative.

Recently, there has been a game added 'Little Nightmare Enhanced Edition' which the developer generously gave away for free to holders of the original. Steam does not quite properly facilitate this however. The Enhanced edition does not hold the same achievements, and if you want to utilise the DLC on the Enhanced edition you need to purchase it on the obsolete edition for it work on the Enhanced edition. So the user (no fault of the Dev) has to manage two version, rather than the optimal position of having one new entry that has the same achievement progress and a library of DLC all within the superior edition.

With Big Picture about to become more popular having new entries pop up on the big screen and causing confusion between which edition may be the suitable can be quite confusing.

When a new edition is released I'd like to see an 'Upgrade' button emerge on the existing entry page. I see some entries (not all) on the store page clearly state 'this version has been replaced'. A similar thing for games already purchased, and a pathway to upgrade would be nice.
1) It does not force an upgrade if free.
2) It provides an option to upgrade (for free if the Dev chooses, or for a fee) and a warning if the upgrade uses a new save system that progress may be wiped.
3) Achievement, DLC, etc all move to the new entry.
4) Following on from point 2, as it is optional, this affords the user to complete their existing play through before upgrading. Or if they have just started a play through, consider resetting their progress on the better version.
5) As it is not automated, the user can review any potential upgrade before they do so to read reviews to see whether the new version is buggy. Once satisfied they can upgrade.
6) In the case of a remaster. The old version is either removed, or hidden. Removed if the prior version is well and truly rendered obsolete such as, it was updated due to the prior version no longer working.
7) In the case of a remake. The old version is not removed as the older version may have some sort of 'classic' value, the user can hide the older version themselves if they deem it necessary.
8) An option to remove the obsolete version entirely without jeopardising the new version.
9) Option to receive an email from Steam when an existing entry has Remastered version released.

I have been playing through my library recently as I've had time to go through my backlog to find a number of games have remasters or newer versions. Only to find this out after my play through in many cases, I may have considered upgrading for a better experience had I have known.