Personally, I’d be happy if LeStrange Pickaxe replaced Bombarda as the most profitable.
The removal of my warps has had a negligible impact on my mining profit per hour. Like I tried saying… the problem was never mywarps. The advantage comes from two factors:
1.) Gravity / vertical mines. Falling is just as efficient a travel method as wearing Voldemort Skull, and you get to keep wearing Bi-Focals.
2.) Haste. With enough sources of haste (passive, vold legs, serious black) the time spent choosing an efficient block to mine is less efficient than just immediately mining while falling into the next block.
Before, I’d often get in position for my next column 2-5 seconds before Vold Legs came off cooldown. Now, I’m consistently getting in position just after the cooldown. I actually prefer mining without the mywarps. I get to keep “/sellall” in my clipboard rather than "/mywarp ".
Regarding Voldemort Skull vs Bifocals:
No amount of speed is ever going to make Voldemort Skull truly worth using over Bifocals. The only way Voldemort Skull is going to beat Bifocals is if it gets a similar effect. The amount of time actually saved by Voldemort Skull enabling you to get to the next block (or pickup those pesky far drops) after a big bomba explosion is never significant enough to make up for the increased revenue generated by bifocals of the vast majority of the bombarda explosions.
If the intent was for Voldemort Skull to be more useful than bifocals for mining, that intent hasn’t been met. Potential buffs could be giving greater mining reach, giving it bifocals ability, or giving it some other passive mining revenue buff that combined with the speed outshines bifocals.
As for nerfing gravity mining, the only options I can think of are to make horizontal mines or remove /top and make the nearest warp a significant walk away. I suppose theoretically bifocals could be nerfed to not work from above. Alternatively, other pickaxes can be buffed to a point that they exceed bombarda’s downward efficiency by a large enough margin to be worth using. Another drastic measure would be to add a delay to mine warps. 
The ideal solution, in my mind, is to just give lestrange a high enough fortune to outshine bombarda. Another solution I can think of is giving some sort of miner’s fatigue to bombarda and making the average explosion larger. This means that choosing blocks becomes effective than just mindlessly aiming down. Not sure how haste and miner’s fatigue work when applied at the same time though.
Also, I’m fine with the removal of being able to mywarp into/onto mines, but not being able to mywarp out of mines is just annoying with no logic. The only thing it accomplishes is making me type /mine before doing a /mywarp to go to golden grass or whatever. It also effects all mining methods.