From SLA. From the table, u can see the value of leasehold as a % of freehold when it comes to enbloc.
http://www.sla.gov.sg/doc/ser/leasehold%20table.pdf
So it your leasehold condo has 1 year term left, it means that it is only worth 3.8% of the value of an equivalent freehold condo, which means either u or your enbloc developer need to pay up the rest of the 96.2% of the value of the land. In short, it is worth almost nothing.If your leasehold condo has 34 years left, you only get 63% of an equivalent freehold, and so forth. The developer will have to pay the govt the 37% for the lease topup. In short, you lost 37% of the value. That is why most leasehold condos rush to enbloc early, because the lease decay increase in an increasing rate.