There are certainly a range of options that exist for dealing with the bottleneck of Colwich / Shugborough and releasing capacity for more passenger and freight traffic.
The original 2a plan is the best - it would drive a high-speed, slab track line all the way from the end of phase 1 into Crewe station. It unlocks significant journey time savings to everywhere north on HS2, Bhm->Man services and provides loads of new capacity for freight. It’s also the most ££. For both political and economic reasons, this probably isn’t coming back.
The re-named 2a-lite or ‘Cheshire Connector’ is the 2a alignment, but de-spec’ed with ballast tracks, smaller loading gauge and slightly slower. Still a great option, but some say not enough money saved / substantially different enough to make it politically possible.
Given that the 2a route basically follows the (already 4-track) WCML from Baldwin’s Gate, another, cheaper option would be to build 2a as far as here, then connect onto the WCML fasts, take these lines over exclusively for HS2 and upgrade their line speed to 140mph. Crewe is therefore reached via a mix of new and existing line but in a financially beneficial way - the most expensive bit of 2a is all the viaducts on the approaches into Crewe, the line south of here is basically open countryside with no major civils (relatively speaking). You get much of the benefit for less cost.
Next up as would be to build 2a only as far as Hixon and join onto the line to Stone / Stoke. This misses Crewe but is even less new line and gets you to Manchester. Doesn’t benefit other northern places though. A variant of this could see a further line divert from this and connect into Crewe to unlock these.
Finally, there is the old Colwich bypass scheme which would see a line divert from the WCML north of Handsacre, cut the corner off and merge with the line to Stone, north of the bottleneck.
All these have way more complex details and have many pros and cons.
Personally I think Crewe is important and given the powers are there to build it, the 2a alignment should be used to get past Colwich. But I think there’s a very real possibility of a significant cost saving by not going all the way into Crewe on new line. The ideas of connecting into the existing lines somewhere south of Crewe should be weighed against the do-nothing and original schemes. Also looking at the prospect of releasing funds to pay for this by abandoning Handsacre.