Announced by a quiet change in the eShop listing.
http://www.nintendoworldreport.com/news/47509/yoshi-delayed-into-2019
Yoshi for Nintendo Switch (working title) was a no-show at the E3 2018 Nintendo Direct. If that surprised you given the game's 2018 release window, there's good reason it's absent from the spotlight: It's now due to come out in 2019 instead.
Along with Fire Emblem: Three Houses this makes two major Nintendo first party titles that have slipped from 2018 to 2019. Aside from the almost stealthy change on the title's eShop listing, no additional details are available yet as to why the game was pushed back when it was already in a playable form at last year's E3. However, there's two more days to E3, so we'll be sure to update this story if more details as to the game's status surface.
I think Yoshi was delayed to fill out the first quarter of 2019
I have a feeling they couldn't find the fun in the game. Everything that I saw felt very generic in terms of gameplay and feel.
I think Yoshi was delayed to fill out the first quarter of 2019
I'd rather they fill out the last quarter of 2018. There are a lot of games that are already supposed to be hitting in the first quarter of 2019. Does Nintendo really want Yoshi to compete in that time frame?
There are no games scheduled specifically for Q1 2019 (just general 2019 dates, or second half 2019 for Pokemon games), so not sure why you think Q1 will be too crowded.