Missing lateral incisors (second tooth from the middle) are fairly common.
I would say no one is too old for braces, I am currently having invisiline and middle aged people are starting to have braces more and more. However, if you don't like the idea of braces, there are other options.
1) Implants - You can have two artificial roots put in and have crowns attached on top. This is the most long term solution, implants last for a lifetime. They also do not damage the adjacent teeth.
2) Bridges - Slightly cheaper than implants. However, cons are that you have to cut the adjacent teeth to put them on and bridges typically need to be replaced every 7-10 years. You will end up paying more in the long run.
it appears that you have prolonged retained baby tooth and permanent tooth is erupting. If permenet tooth is morphologically intact, permanent tooth will erupt to where space available after removal of baby tooth.Once permanent tooth reaches full eruption, you can place a crown to achieve your cosmetic demand.