From 2016 to 2017, Erdogan arrested and sacked more than 160,000 people from government jobs(civil and armed) and universities.
How is Turkey, as a country, going to fill this huge blank of human capital in?
Turkey's unemployment rate is about 11% and it's working age population would be about 48,000,000 (I'm using about 60% of the population as an estimate) so filling 160,000 positions is just 3% of roughly 5 million unemployed.
So numerically it's a trivial task.
In terms of replacing skilled positions, it's simply a matter of promotion. Inevitably some reduction in overall skill may occur, but in practical terms this is unlikely to be significant overall. There are always going to be people who are seen as significantly more experienced who leave, retire or, in this case, get the boot, but life goes on and it's unusual to see total disaster resulting when even someone considered a leading expert leaves an organization.
However as the primary aim of the removals seems to be a combination of security and politics, it's unlikely that any loss of skills will be seen as an issue for the people (person) at the top.
It's debatable that the loss of skills with a specific grouping of political or moral viewpoint might be more damaging than simply the skill loss, but, again, that's not going to significantly impact the decision maker(s).
@Philipp made a comment :
The problem is dealing with the chaos you create when you remove 160,000 trained, experienced and integrated people from the public administration system overnight and then try to find, hire and train replacements for them that quickly
You promote (or externally hire) people with the best skills you can. By promoting people up you essentially reduce the level of skills actually lost overall. The lowest grades are easily replaced and trained. So the effect is, in practice, minimal.
Public administration systems are generally quite robust when it comes to senior positions being vacated and filled.
The replacement of university and teaching position is probably more significant, as is the effect on media. While it may be politically desirable for the current administration, I'd expect these purges to have a detrimental effect in the long run, as it makes people reluctant to do what's right over what's politically expedient. But that's an essentially unprovable opinion of mine.
The most significant impact of these purges has been that the EU has suspended negotiations with Turkey on EU membership. There may be more impact, but the need to have Turkey on-board in the fight against ISIS means that Turkey is politically in a good position to avoid significant sanctions.
So overall the effects of these purges would seem to be negligible beyond the long term political health of Turkey.