Xīn lǎo yuángōng de gēngtì shì gōngsī fāzhǎn de chángtài.
The turnover between new and old employees is normal in company development.
Tips
usage
Note 更 is read gēng (1st tone) here, NOT gèng - same character, different reading, different meaning. As gēng, 更 means 'to change/replace'; as gèng, it means 'even more'. 更替 is slightly literary; in everyday speech 替换 or 交替 are more common.
mistakes
Don't read this as 'gèngtì' - that's wrong. The verb-meaning of 更 is always 1st tone.