Linux has very bad scalability. Linux scales excellent on SGI UV3000 and similar servers, but they are scale-out clusters capable of only running clustered HPC workloads such as number crunching, BI analytics, etc. Such clusters can have 10.000s of cores because HPC workloads are easy to parallelize. So you want many cheap cpus (x86). Typically, scale-out UV3000 serves one scientist at a time, doing a 24-48h number crunching workload.
Enterprise business ERP workloads (SAP, OLTP databases, etc) can not be parallelized, you need a single large scale-up server for that. So you want few strong cpus (RISC). Scale-up servers typically have 16 or even 32 sockets and run SPARC/POWER or IBM Mainframes. Look at the SAP benchmarks, the top all belongs to Unix with 32 sockets RISC. There are no single Linux x86 server doing high SAP. Typically, scale-up business servers serves thousands of users simultaneously, doing accounting, payroll, etc.
Look at the SGI use cases on their web page, all the UV3000 customers are doing HPC clustered workloads. No customer is doing SAP or OLTP databases or other business workloads. Google if you want. So a large Linux server with 10.000 of x86 cores can not beat Unix 16 or 32 sockets on SAP, OLTP databases, etc. Linux scales up to 8 sockets on scale-up x86 servers, but not more. If you need 16 or 32 sockets, you must go to Unix and RISC. The Linux devs have only access to 1-2 socket desktop PCs. There does not exist large 32 socket Linux x86 servers, so Linux can not scale good on 32 sockets, because the devs can not optimize Linux to 32 sockets.
And we all know that Oracle is only doing business servers (which require scale-up). And we all know that Linux scales bad on anything larger than 4 sockets scale-up. So when Oracle is releasing 16 sockets, 1.024 cores, 8.192 threads, 16 TB RAM for the M7 servers - Linux can not utilize all that business power. Only Unix can (Solaris, AIX). So if Oracle is canning Solaris, then Oracle looses the ability to run large business workloads. Oracle can not sell large business servers without Unix because only Unix can run large business workloads.
Look at SAP benchmark top list, the top is Unix and RISC. Linux and x86 is far below. Recently, HP has redesigned their HP Integrity Superdome RISC Unix server which sported 64 sockets, and instead inserted x86 cpus. But the new HP Kraken server, stops at 16 sockets, whereas Unix went to 64-sockets. The highest x86 SAP score is HP Kraken, a redesigned Unix RISC server. Other than HP Kraken, the largest x86 server has 8 sockets, and those SAP scores are bad.
In short, if Oracle kills Solaris, then Oracle can not sell large Business servers longer. The largest Oracle database installations in the world are exclusively running on Unix / RISC servers. There are no large Oracle database installations on x86 running Linux. Exadata is quite small, compared to the largest Unix RISC database servers.