My wife (eks-wni) and I also consider to retire in Indonesia with about 50+ (yes, we know about the visas, even detailed...) and we also have made our budget, what will be, if we stop working in the mid 50ths and live then from savings and rent out properties back home. Also, our current home country has a double tax treaty with Indonesia which does not make things easier. Taxed here in Europe by a rate of approx. 10% of taxable income, it will be in Indonesia 35%. Plus the all day and everywhere 'pajak-bule' that I'll face too.
We have considered several countries for retirement and for sure, Indo is number one because of my wife's former nationality, but in fact, there are other countries which make retirement a lot easier. After checking Malay (too expensive), Philippines (to insecure), Laos or Vietnam (not developed enough) we could also life in Thailand and connect more to the expat community, as integration into the local society will be very difficult. We think, the overall development and standard compared to Indonesia is a bit higher, prices are approx. the same, but the tax is a blank zero on savings from last year.
Honestly, if I'll have to get a NPWP and if I'll have to pay the 35% taxes of my then already not so big income, then I'll head up for Thailand as a home base with a yearly visa and just travel forth and back to Indo.
And I'm pretty sure, that allot of other pensioners in Indonesia will then have a problem too.....