Read 6 comments as:
1. How would this affect placements and vacation schemes for Indian Students in Allen & Overy?

Shearman even thou having a london office only takes US/EU/UK grads.

2. How will this merger work - both these firms have very distinct cultures, billing rates and even salaries - how will all this work out? Are there any real advantages for the merger.

https://www.reuters.com/markets/deals/ao-shearman-merger-would-be-blockbuster-maybe-not-harbinger-2023-05-22/
Check facts. Shearman has frequently selected(if not very consistently) graduates from

Nalsar (sometimes nlsiu). Now they have also expanded to JGLS for some reason.
1. This will not affect training contracts/vac schemes. For all practical purposes, it is business as usual for the A&O's offices located outside North America. Bulk of Shearman's revenue (and lawyers) is in the US and that's where you will have an impact on personnel, hiring, offices etc. A&O is not going to start hiring more Indian grads because of the merger.

2. Don't think of this as a merger. If you read between the lines, it is apparent that this was a classic PE style acquisition of a blue-chip brand now in distress. What A&O have always chased, and have now got, is a substantial presence in the world's most lucrative legal market (i.e. USA) and the roster of American corporate clients that Shearman brings to the table + Shearman is still a very strong shop for corp and litigation work in the US. Everything else is just noise. Culture/vulture all can be managed when people see the $$. Billing rates are dictated by the market that you operate in and not the firm.

What will be interesting to see is how they manage to keep the partnership broadly happy with their new comp structures. There will inevitably be a dilution of the value of their partnership points and bunch of partners who will take home less cash post-merger.
From these paragraphs of analysis i can assume you are a partner
Shearman PPP is more than AO. FYI. Atleast as of 2022.