Please specify the reasons due to which you will think Tejas will be delayed. What is the upgrade in MK2 that you expect to cause delays.
The way I see it, MK2 is just a bigger Tejas and nothing more. It is the subsystems like AESA, EW, engine that is the concern. And these are same specifications for MK2 and MK1A and hence can be developed in parallel.
Speak with reason and evidence. MK1 is rolling out already, FYI. Take this into consideration too
Lets start one by one :
1). IOC-1 certified in 2011 and IOC-2 in Sept month of 2013 and we are still waiting for FOC in 2017. FOC requires :
a) BVR :- I hope thats done and HAL is probably looking to further improve precision and software update.
b) In-flight refueling : The probe has been attached to LSP-8 and flight test already done, BUT, there is no news regarding the refueling test from last 2-3 months, it should have been conducted by now.
c) Gun fire : Only ground test done, no news regarding integration yet, inform me if there is any I havn't come accross.
All this development took more than 6 years and that to in indigenously designed jet. Thats pathetic.
2). MK2 is just "Bigger Tejas"!!! This shows your understanding about fighter jet, even I am not an expert but at least it is basic knowledge that even a centimeter added in jet has big impact on aerodynamics. So do not expect IAF to give easy clearance to MK2 and expect HAL/ADA to spend years in perfecting the aero data.
3). Now lets talk about MK1A, its specification is offered by HAL, not IAF. HAL's promises to reduce ~200 kg empty weight, but there is no official statement regarding this yet, I hope NDA effect, they are already using composites i.e. 45%, I don't know from where will they reduce that 200 kg, if they even do it, how much time will HAL require to re-certify the MK1A, as this will change the aero performance by big margin.
4). Only positive is that MK1 is under limited production and slowly and gradually getting accepted by IAF as "step-son".
I won't risk getting too optimistic about MK2 due to the first point.