The default replacement for Flash is the use of HTML5, this is, and has been for some time been part of the Current batch of Browsers, so it should not need any input on your part, unless you are not using one of the later browsers.
As always with the Internet there are some content providers who will go their own way, but if they do this then it is up to them to provide the required software,
Beware those giving away the latest "Flash Player Replacement" or those Charging for their specialist software