Sri Lanka tasted a new success after a long time, actually they performed better in the last 2-3 months, so they are in good form.
South Africa is also upping their game. England and Australia are already terrific sides. Pakistan can surprise anyone. India is a big team but in ICC tournaments they are choking since 2013-14. Then we have Kiwis and Windies. Safe to say that this T-20 WC is going to be a belter.
On records yes I agree Australia is exceptionally best in the ICC tournament. Srilanka might have performed better in the last 2-3 months but I still think they are not a team that can be considered as the top 4 probably who could win the upcoming world cup. In my opinion, the 4 are England, Australia, India, and the Kiwis. Still, any team can suddenly outshine their performance.