If engineering was deleted from the game overnight, I don't think it would effect many at all. We would all quickly get use to the new ceilings, we would each have our individual meta builds, they would just be different to what we had with the Engineers. In other words, WE WOULD ADAPT, just like we did when Engineers was introduced.
As for the idealist dream that nerfing Engineers would somehow get rid of gankers. Nope, can't see that happening. We are talking about a group of people who think it is enjoyable to attack inferior ships, to fly around stations ramming people in their free Sidewinders. Get rid of engineering and all that would happen is these low life's would just revert back into flying around in A rated meta builds looking for those in weak, lower spec'd ships (and of course religiously avoiding any ship that might pose a threat to them, after all aren't all gankers just reverting to their schoolyard bully persona)
You are right on the second part. Removing engineers would merely be an inconvenience to the gankers, but it would not stop them. If anything, it might result on one of them occasionally being blown up, as his FDL doesn't have the defences any more which somebody of his skill level needs to survive the withering firepower of a Hauler...
On the first part though i dare to disagree. I mean, there was a time before engineers. The game was live for two years before they were introduced. So it's not like "no engineers" would be pure speculation. We do know how things were at that time. And while indeed many people also gravitated towards meta setups, there were a number of those around. Without blueprints so dominantly dictating which setup is so much more survivable than any others, a much bigger diversity of setups was viable and being used. A number of vastly different combat stypes were used.
Blueprints and the overwhelming effects of stacking effects eliminated them. They hit the wall of +800% or more of defense increase, which they just were not able to overcome. Engineering blueprints completely changed the game and eliminated many formerly used options, without granting actual new options of gameplay. All it brough was power creep, while supporing a much smaller diversity of setups than before.
This is not speculation. This is how the game was. I mean, the game now has many more ships than in 2014. But if you go back to the very old meta discussion threads of that time, you will see that the actual number of ships being used in meta setups was much higher than it is today. And many of those ships even had several vastly different setups (shieldtank, hulltank and stealth fighter were the most common things around, but there were much wilder setups which were also considered to be viable) which were seen as valid choices.
So yes, i know that FD will not ever, even when their companies survival would depend on it, undo what they did with Engineers. But it's not mere speculation if the game would be better and if ship diversity would be higher. We very much observed the introduction of Engineers and at first hand saw the resulting changes. And they were not good.