When I talk about my dream of building the best DNA assembly system ever created, the most common response is to ask “won’t that be obsolete once DNA synthesis gets good enough?” It is a fair question, but I also think it is rather lazy if you try to think about the relationship of DNA synthesis to DNA assembly. Those 2 do not directly compete with each other - DNA assembly is important and will continue to be important for a couple of reasons.
A significant amount of users do not have access to the world of DNA synthesis - for example, in Latin America, Africa, or certain parts of Asia, where it can take weeks or months to even get oligos. In the United States, many users can’t afford pure DNA synthesis right now, while assemblying parts is an affordable way to achieve what they need (and you should never underestimate the hobbyists). In a way, using DNA assembly rather than just synthesis is akin to using a data cache when serving large applications from servers. While not strictly necessary, it gives a large enough boost in productivity to be worthwhile.
On the other side of the resource equation, high resource users want the efficiency of using high throughput combinatorial assembly in order to realize biological functions. This usually involves a combinatorial search with a large variety of different DNA parts, selecting out the best functioning ones. This activity cannot be subsituted by DNA synthesis - it requires a DNA assembly platform to accomplish because it is literally assemblying DNA parts. Those parts can come from cached DNA parts or from raw DNA synthesis, but a DNA assembly pipeline is still needed.
DNA synthesis, right now, is also driven by factors beyond just building DNA for organisms - for example, DNA data storage. These markets aren’t selecting for clonal DNA selection, and so investment within DNA synthesis companies often points towards getting better at the synthesis aspect, rather than getting better at the delivering clonal DNA to people.
I think the opposite may actually be true when it comes to DNA synthesis and DNA assembly - improvements in DNA synthesis do not obsolete DNA assembly, they improve DNA assembly. We’re on the cusp of DNA synthesis massively improving the world of assembly, and I can’t wait to work out the bugs!
(Quick answer on why DNA synthesis improves DNA assembly: The usefulness of DNA assembly is dependent on the number and quality of DNA parts that are available, and previously most DNA parts were locked down or hard to get. DNA synthesis enables production of a massive amount of DNA parts, which makes DNA assembly more valuable)