The goal is probably to deliver all I-Class by 2028-2030 and then start production of the first TF-2000 destroyer.
I'm still expectin a design by the Navy to slot in between the I-Class (3100 Tonnes) and the TF-2000 (8000-8500 Tonnes)
5000-6000 tonnes design with 6-8 ships to supplement the fleet is necessary imo.
You could split the class between AAW and ASW or just do Multirole for all.
It is up in the air if we will truly see 8 TF-2000 to replace all 8 Gabya ships, I dont believe so honestly.
So maybe going
4+2 TF-2000 ----> partly replacing Gabya
6+2 5000-6000 tonnes design split AAW and ASW or straight Multirole depending on needs---->partly replacing Gabya with the AAW compartment and adding to the fleet
8 I-Class Frigates ---> replacing all Yavuz and Barbaros ships
4 Ada-Class Corvettes
10 Hisar OPV ---> some fully armed most FFBNW
Unknown numbers of new FAC
I'm honestly afraid they will shrink the fleet due to budget problems or keep it at the same number by going ship for ship.
With you much more active the Navy is I truly hope they find the money to expand it. Or else all our endeavors are for naught if we can't actually back them up with credible presence.
But these are just my hopes. Everything can change depending on how the economy goes the next couple years.
Italians are building 6 Constellation Class Frigates for the US Navy. Greeks wish to dovetail on to this programme with a possibility to build some of them in Greece. These are derived from FREMM Class and are 1.1 to 1.2 billion dollar, 151m long, 7300ton ships with 32 VLS tubes.
By the time we start building and finish the first 8500ton TF2000 destroyer, we may see a ship that is upwards of 1.5 billion dollars a piece. Complicated radar, electronics and weapons systems being developed each year, are seeing the cost of modern ships spiralling up in to levels that are becoming too expensive to build. Our I-Class ships are probably touching 550million dollar mark now. (However, by building 7 of them together we may be economising a great deal)
When we had 16 frigates; 8 x Gabya, 4 x Barbaros and 4 x Yavuz class, we were not envisaging showing force in Qatar and Somalia and going in to operations in Libya. Now that we are reaching further afield and having to defend areas in Black Sea as well as Eastern Mediterranean, 16 frigates are not enough to project force. Especially as we now have a large amphibious assault ship to protect and another one being programmed in the pipeline.
For coastal defence and littoral waters, 10 OPVs and 4 Ada Class Corvettes together with 10 new FAC boats like FAC-55 and 16 Tuzla Class ships with some of the old FACs like Kilic Class will do the job.
But for aerial defence and force projection further afield, we will see that, 4 Gabya with VLS will still stay in service for a while. These are 4100ton 136m long ocean faring frigates. And are very capable.
Yavuz Class will be replaced with the first set of 4 I-Class ships.
4 x Gabya class without VLS will probably be replaced by the second set of 4 I-Class, unless we delay building the 4 large new frigates/destroyers..
4 x Barbaros Class MEKO200 ships, having gone through MLU, will stay in service for at least another 15 years.
To supplant the TF2000 with a cheaper version we may add 4 heavy frigates to the fleet that are shorter and lighter version of these destroyers, and are more affordable to build.
As you have mentioned in your last paragraph there are constraints such as budgetary and political that will govern the outcome.