These pages are similar but unlike the existing company pages where all products are on one page, Showcase pages are all separately indexed and displayed as separate items associated with a Company page.
The deadline for making the switch is April 14th which is just a few days away. If you haven’t already created your Showcase Pages you should do so while you can still reference the old products and services tab as a resource. There is a glitch that LinkedIn is aware of that only allows you to create two Showcase pages per day under one profile. If you manage many pages you will have to log in as another administrator to create the pages. There are many discussion threads out there about this problem that I don’t feel you need to spend time reading.
My recommendation is to start your pages as soon as possible and continue each day until they are complete. This will get you situated for the switch without any hiccups.