A easy question for Ci4.0 ( can i Upgrade from Ci3 to Ci4 ?)

I think this is one easy question, because i hope to sure for my project so i must create this topic question 

Question: 
I am in a Project which is building on Ci3.0.6, rummor about Ci4.0 will was born in next times, my question is may i update my Project from Ci3.0.6 to Ci4.0 ? ( My project about Mini Supermarket, i has only created files in Library, Helper, Controller and Models )

Please can tell me can i sure to Upgrade my Project from Ci3.0.4 to Ci4.0 ? That is very important to me because my Project will Complete at middle of next year but in that times the Ci4.0 can be republic 

Please help my small brian !  verry verry thanks

i am vietnamese so not pretty about english