2020 will mark an end of an era for Flash, but one that feels like it has been a long time coming. HTML5 standards have been implemented across all modern web browsers, and the need for Flash just isn’t there anymore. An end to Flash will bring with it obvious improvements in security and just pure battery life on laptops and other mobile devices that still support the web technology.
So you should just find an online conversion tool and upload the content, right? Wrong, because you are putting your intellectual property at risk. A lot of online programs hide specific legalese in their terms of service that grant them the ownership of the content that you upload in exchange for the conversion. This happens often with online PDF converters.
Another factor is the content and the layout. Most simple converters will miss or mash together the content and file structure in order to compress the file and make it easier to upload and download. There’s no assurance extra code isn’t injected creating a backdoor vulnerability that can be exploited in the future.