It is also trivial to emulate these days, so to me I don't see any potential lost sales. Worst case it reveals some mostly already suspected story details that were cut or left unstated in the final versions. MGS4 might still have some value because you need expensive hardware to emulate decently and it isn't perfect still. But a 15 year old computer can emulate MGS2 better than it originally ran on the xbox.

Do you think this leak will harm sales of the Switch 2 version?

Konami willing, they'll drag the IP to their grave. Lest we forget MGS3's first remaster... for Pachinko parlors: https://www.youtube.com/watch?v=VsJ4QgBpQN8

Recompilation efforts raise the bar for future re-releases, and incentivize proper remaster efforts like MGS Delta instead of the half-assed Master collection. I would love to see Konami thrive as a company and get more people interested in MGS, but their recent re-releases don't deserve to be priced at $60. Their monopoly of the source code feels like an existential threat to both future preservation and high-quality MGS remakes, it's healthier for Konami to simply let it go at this point.