Yes Peli you are correct - you could in theory get a 90/180 visa at the start of your holiday for a short period and then return to complete the remainder of the 90 days towards the end of the 180 days, then you would have to either leave or go to Rhodes on day 180 (but stay overnight) and then get another 90/180 visa which would let you stay for another block of 90 days - which theoretically gives you 6 months as a block or thereabouts. Sounds too complicated to me easier to get a residency visa if you intend to stay 6 months in a block!
Obviously the aim behind this new visa is to encourage people to get their residency visas, and I believe that if you wish to stay for 6 months or longer then you should be getting the residency visa anyway. There are obviously cash incentives for the Turkish Government in that more people will be getting residency. Not sure how happy the ferry service to Rhodes will be as they will see quite a dramatic loss of their income.
I've applied for citizenship which so far has taken over 9 months and counting, I've been for my Turkish test and interview, just waiting for the bods in Ankara to sort themselves out! Apparently it can take one year or over to process! When I get that it will mean the end of visas for me plus I can work legally !!
JT - confused? You will be! Wait until it is enforced .....
Chris