Microsoft confirms Skype has been optimized to work on older Android devices
The new version of Skype is smaller in size and eats less memory, thus allowing for greater speed and better audio and video quality on budget-friendly Android devices. Moreover, Microsoft promises the lighter version of Skype will offer increased performance even in areas with “challenging network conditions.”
It appears that Microsoft will kick off the roll-out of the update in the next few days, but it will most likely take weeks to arrive in all regions. So, if you don't see it on your Android device soon, don't worry and be patient.
Those who absolutely must have the new version of Skype before it goes live, can sign up for the Skype Insider Program and take advantage of the new experience offered.