Well, seems Microsoft has enough of tweaking by Modders to its Windows 10 Mobile Android subsystem better known as Project Astoria. It has simply removed Astoria from latest Insider Preview build 10549.4. This has been reported in XDA Forums by Modders.
If you remember, Microsoft patched the Build 10536.1004 in such a way that it became impossible to run or install Android applications. But like always XDA community had found a solution. But this time since Astoria has been removed so only way to get Astoria back may be by manually importing it (which is very risky) or going back to older builds by recovering to Windows Phone 8.1 and then choosing “Slow Ring” to get Build 10166, one of the better Windows 10 Mobile builds.
There is one more school of thought regarding why Microsoft may have removed Astoria. Build 10536.1004 suffered gradual degradation in performance over time and we know that happens with Android. So, some may think that real reason behind Microsoft decision may be to debug and test the new build without Astoria.
Thanks Riko for the tip. Cheers!!