Niche site expanding it's topics - split domains - benefits vs risk?

Need some insight from experienced SEOs. I have a highly successful niche travel website, it's grown to become the highest-ranking site for that niche. But this year I've been experimenting with off-topic broader articles and they've been ranking really well, for example, I've been able to outcompete most of the other sites within those topics after 2-5 months of publishing these articles. Once I realised I could rank for the more general and more competitive keywords, I started writing more articles with the plan to transfer these articles to a new domain during the "off-season" for these keywords, which is now. Why a new domain? A few reasons, but mainly because I want to grow these new articles as a new website and my current domain name includes the name of my niche, so when these new articles pop up on Google they look less relevant and kind of off-topic... Not entirely off-topic, the domain is the niche name + country name, but the new articles are general travel articles for that same country but not related to the niche, the niche is slightly travel related, however. So now the time has come to create my new domain and website. But I'm so worried about losing all my rankings and traffic, and therefor, my affiliate revenue. I'm also worried about the time it will take to recover my rankings. Are these fears unfounded? If my article is ranking in the top 10 for competitive keywords, how long will it take for the exact same article to achieve the same ranking on a new domain and website? Would love to hear any experience, advice, or tips regarding this. Much appreciated :)