First of all you need read the first 3 articles than read the 4th article which answers some of your questions.
I. Form of the State
ARTICLE 1- The State of Turkey is a Republic.
II. Characteristics of the Republic
ARTICLE 2- The Republic of Turkey is a democratic, secular and social state governed by rule of law, within the notions of public peace, national solidarity and justice, respecting human rights, loyal to the nationalism of Atatürk, and based on the fundamental tenets set forth in the preamble.
III. Integrity, official language, flag, national anthem, and capital of the State
ARTICLE 3- The State of Turkey, with its territory and nation, is an indivisible entity. Its language is Turkish. Its flag, the form of which is prescribed by the relevant law, is composed of a white crescent and star on a red background. Its national anthem is the “Independence March”. Its capital is Ankara.
ARTICLE 4- The provision of Article 1 regarding the form of the State being a Republic, the characteristics of the Republic in Article 2, and the provisions of Article 3 shall not be amended, nor shall their amendment be proposed.
^^^ Other articles can be changed but nobody can touch the first 4 articles.
Regarding discussions on "new" constitution, we don't know. Erdogan is keeping that to himself. He just said "maybe it's time for a new constitution" nothing more.
To change the articles in the parliament they need 2/3 of the votes which makes
400 out of 600 votes.
To change the articles by a referandum needs 3/5 of the votes which makes
360 out of 600 votes.
AKP and it's ally MHP have 337 votes in the parliament. Forget changing it themselves, they can't take it to referandum.
Türkiye Büyük Millet Meclisi Resmi İnternet Sitesi
www.tbmm.gov.tr
Many commentators and i think that he is just trying to divert the attention from ongoing economic crisis, nothing more.