Q:

Can we have MathJax back? 

It's been a couple years since PPCG voted against MathJax.  Since then, the vote ratio has changed significantly, and most seem to be in favor of MathJax.  However,  it is status-completed and no change will be enacted on the current votes. 
The issue then was weird-looking search results, odd indentation and broken stack snippets due to $ being used in code.  There are solutions to most of these, however.  One solution is to escape all instances of $ in code (like it's done with < and >), which sounds fairly tedious but most of the work could automated if TIO were to do it.  Not a great solution but some might believe having MathJax outweighs the cons. 
We've had a lot of math questions (and answers) since and they would greatly benefit from having actual mathematical expressions that look ridiculously better than if they were done with meek markdown formatting. 
I'd like to revisit this issue with another vote as opinions and ideas have changed since then. 
Should MathJax be enabled again? 
Please vote on the answers with approaches, not on the question based on your opinion on Mathjax. 

A:

Yes, bring MathJax back
Advantages of having MathJax on Programming Puzzles & Code Golf:

A lot of math, number and number-theory challenges and answers (and not only those!)  would benefit from having it back.  This is a lot – At the time of writing, about 12.19 percent of the challenges are mathematics-related, not to mention that math is our third most frequented tag. 

Rather than having to type our maths using third-party services, and then uploading pictures which would clutter the entire page, while still not being completely aesthetically pleasant, we would have a built-in way to use these equations that would overall bring a design improvement to the entire site. 

Disadvantages of having MathJax (mostly those that were mentioned in the 2015 post that has disabled it) and their possible solutions (but they no longer seem to apply):

Snippets that contain $ would mess up the search query and / or markdown.  As pointed out by Doorknob, the fix is easy.  Use \$ or other separators instead of $ for starting / ending MathJax passages. 
Code snippets containing $$ are a problem – unless the escaping issue has been addressed since 2015, not sure – the separators for non-inline, centred expressions are not site-settable.  I am sure we would find a work-around, though, because stack-snippets and the search query are still two very important features of this site.  If this would still be a problem, we could simply just use inline math with \$. However, the fix is rather easy as discussed in chat. 

Example Answers and Challenges that would take advantage of it

Calculate the number of primes up to N by Dennis. 

(-a) × (-a) = a × a by Wheat Wizard. 

Absolute Sums of Sidi Polynomial Coefficients by Dennis. 

Some answers to One OEIS after another by caird coinheringaahing. 

Largest Number Printable by Vereos, and all its answers. 

Determinant of an Integer Matrix by Leaky Nun. 

How lit is this mountain?   by Mr. Xcoder. 

Coprimes up to N by Dennis. 

Golf a transcendental number by xnor. 

Approximate definite integrals using Riemann sums by Mr. Xcoder. 

And the list goes on.  As you might have seen, challenges and answers from various tags, not only code-golf would have a benefit from re-enabling it.  Now, we can’t just exempt this site from having nicely-rendered mathematical insights, purely due to some separators, right? 

A:

Add support back, but change the delimiter
I think MathJax would be fine, and see Xcoder's answer for more reasons why.   However, the reasons it were disabled still stand:

Messed up regexes, since MathJax can trigger inside code blocks for whatever reason

Odd-looking search results (though in general I think this applies to regexes in search results)

Breaks stack snippets that we have, including the leaderboard one. 

But as far as I can tell, all of these would be fixed by changing the delimiter.  Something like \$ would work, but I'm open to other suggestions. 

A:

Add support back, but make it not trigger in code blocks. 
As far as I can see, this is the root of all problems.  @200_success on CodeReview Meta says (emphasis mine):

MathJax is currently enabled with $ … $ as delimiters.  However, that breaks existing posts that contain two dollar signs within the same paragraph, but where the code is not formatted using backticks or a code block. 

...which makes me think that this, IMO proper, fix is easily achievable.