Dota 2 may get Source 2 support soon
Information posted by the SteamDB website indicates that Dota 2 could soon be running on the Source 2 engine.
The site lists several "changed depots" for the game that reference "Source 2 Dota 2 Content" for 32 and 64-bit Windows, as well as Mac and Linux, in multiple languages.
The impact of that is currently a matter of speculation, but as VentureBeat explains, Source 2 is essentially an updated engine and toolset used for game and content creation. Dota 2 is built on the Source engine, so a move to Source 2 could mean new features, more advanced graphical options, plus a wider and/or more flexible range of tools for mod makers.
Valve announced in March that the Source 2 engine will be free for everyone, with the proviso that any games made with it must be sold through Steam.