Twitter CEO Jack Dorsey revealed that the company has been discussing how an edit feature could affect the platform. At a town hall event at IIT Delhi, Dorsey made a brief statement discussing how editing tweets could work.
One of the reasons why Twitter has not yet introduced an edit button is for preservation of content. Forum administrators often lock threads to prevent users from deleting or removing all valuable content from posts. As a public forum comprised of short posts, Twitter is no different. Removed content can lead to broken links and lower rankings from search engines due to issues crawling a site.
Dorsey finally seems to be alright with having an edit feature, but will not be favoring a solution that allows editing of old tweets. Instead, it is likely that tweets will only have a short window under which they can be modified. "We have to make sure that we are actually solving the predominant reason why people do it first and not make something that takes away from the public record, because I think it is really critical that we preserve it."
Editing to fix a typo or link could prevent having to delete a tweet and repost it. For regular users this is not a big deal, but celebrity status individuals that have millions of followers routinely are caught doing this by their fans. YouTuber MKBHD is just one notable personality that has been calling for an edit option for quite some time.
Even though it is not likely for older tweets to be edited at all, there are some other possible options that could be taken. For example, a change log of all edits could be made available so that anyone could verify the original contents of a tweet. This could help prevent abuse of such a feature.