The evolution of financial technology, colloquially known as fintech, has significantly transformed the banking landscape. It has improved efficiency, convenience, and cost-effectiveness by disintermediating traditional banking processes. This revolution has particularly benefited small businesses, which were historically underserved by conventional banks.

Online banks, also referred to as neobanks or challenger banks, have been at the forefront of this transformation, offering a tech-savvy and customer-centric alternative to traditional banking. As we delve into the future of online banks for small businesses, it's essential to understand and analyze the patterns of this burgeoning wave, the trends it's establishing, and the potential trajectory it could take.

Online banks primarily operate on a digital platform with minimal physical touchpoints. Although they function similarly to traditional banks, the distinguishing factor lies in their operational model. They leverage advanced technologies like artificial intelligence, machine learning, and blockchain to streamline their services. Considering the Capgemini's World Retail Banking Report, which noted a 63% increase in positive customer experiences with neobanks, it's clear that this operational model is well-received.

The advent of open banking, a system where banks open up their APIs to third-party developers, is a significant trend shaping the future of online banking. It allows the creation of a unified data network between banks, thus improving financial transparency. This development is particularly beneficial for small businesses as it simplifies processes like accounting, payroll, and financial management. Open banking is poised to evolve further with advancements in data sharing and security technologies.

The decentralization of financial services, another emerging trend, is set to redefine the future of banking. As blockchain technology becomes more mainstream, it offers the potential for secure peer-to-peer transactions, eliminating the need for intermediaries. For small businesses, this could mean lower transaction costs and faster processing times. However, the full adoption of this technology is contingent on regulatory clarity and public trust in such systems, which might require a generational shift in attitude towards banking.

Artificial Intelligence (AI) and machine learning are other tech stalwarts set to transform online banking. AI can automate various banking processes, reducing human error and increasing efficiency. For instance, AI-driven chatbots can handle routine customer inquiries, allowing bank personnel to focus on more complex issues. Machine learning, a subset of AI, has the potential to understand customer behavior and tailor banking solutions accordingly. It could also be instrumental in detecting fraudulent transactions, thus enhancing the security of online banking.

Despite the optimism surrounding online banks, there are certain challenges and trade-offs that they need to address. One of the significant concerns is cybersecurity. As banking operations shift online, they become vulnerable to cyber-attacks. Although technologies like blockchain and AI offer enhanced security, online banks need to continuously invest in and update their cybersecurity protocols to keep pace with evolving threats.

Furthermore, the regulatory environment for online banks is still evolving. While the absence of a physical presence reduces the regulatory burden, it also leads to a lack of clarity in jurisdiction-related matters. As online banks grow, they will likely face more regulatory scrutiny, which they should be prepared to navigate.

In conclusion, the future of online banks for small businesses is bright and promising, marked by digitization, innovation, and customer focus. However, it's not without its set of challenges. As online banks continue to evolve, they must balance their growth and innovation with robust security measures and prudent regulatory compliance. The journey towards this future might be marked with uncertainty and volatility, but the potential rewards make the endeavor worthwhile.