One issue I can forsee is this:

Skiff:
Will be the new "highsec" afk mining boat, since you just deploy drones and afk mine. Gankers would need to bring 2-3 ships to take it down.

Mack:

The mack would propably not drop in usage, since it has a fairly large ore hold it would remain the main miner in high, along side with the new skiff.
Because you can mine for a much longer timer, and not worry about jumping to station, to unload, the Mack will be the main one to use.

Hulk:

As it has been since you decided to change the hulk, this ship will be scarce to see in highsec/low/null. The very low tank it has will allow a 2-3 month char, in a destroyer, to kill it effortless in highsec. The priceloss for the miner is staggering(several hundred millions), whereas the loss on the new char is a minor change to security status and a new destroyer(which is less that a million).
One of the issues with the hulk is that the risk/reward on it is just not worth it. The difference in yield is fairly low, compared to the other barges. Considering it only has 2 low slots, compared to 3 lows on the other ships.
If the hulk is supposed to be "king of the hill" in mining, shouldn't it be improved in such a way as to have sustainability in the belt, and a mucher higher effectiveness in yield as well?

Ggeneral thoughts:

For a miner it is all about the isk/hour ratio. The longer you can mine in a belt, and not use time warping to and from a station, is the best for a miner.

As it is now, and in summer patch, the skiff/mack, will be able to sustain mining in belts with little to no effort. Ganks will drop drasticly in highsec, because it is more expensive for the attacker. However, the hulk will still be nowhere to be seen in high, since it can be blown up by a blasterfitted destroyer with little ease. Low-sec/Null-sec will show more use of the skiff/mack since the drone bonus will just make a massive difference, and since the tank/ore hold will be more or less unchanged, there is no reason to switch to the massively expencive Hulk.

When you mine in highsec without a hauler to help out, you are more or less forced to jump to station every once in a while to empty your ore hold.
Each "unloading process" to the station, takes about 2 minutes time. Warptime -> Unload in interface -> undock and warp back. my record is about 2 mins in finanar.
A skiff/mack, would take about 5/9 cycles before it needs to warp to station to dump the ore.
The Hulk would only be able to do 2 cycles, before it has to unload in station. This would mean that every 2-3 cycles(1 cycle is about 180 seconds), you would nee to fly to station to unload, compared to every 5/9 cycles(900/1720 seconds).
The time used on "warpin, and warpout" would mean that every hour, about 30 minutes is used in moving your ship back and forth. Which means that you effectively get only 30 mins of mining.

The numbers are not entirely correct, since you have implants and bonuses and such. However. If you do that math, you will realize that the Hulk is not a viable mining ship unless you have 2 of them and an Orca as a minimum.

As it is now, only few mine in hulks(brave or stupid), because it is a juicy target you can kill very quickly, and the penalty for doing so is fairly low(because of the mechanics of eve).

Anywho.. thats all I have to say atm.